system

    Dark Mode
Search:
Source   Edit  
Deprecated: assertions is about to move out of system; use `-d:nimPreviewSlimSystem` and import `std/assertions`.
Deprecated: io is about to move out of system; use `-d:nimPreviewSlimSystem` and import `std/syncio`.

The compiler depends on the System module to work properly and the System module depends on the compiler. Most of the routines listed here use special compiler magic.

Each module implicitly imports the System module; it must not be listed explicitly. Because of this there cannot be a user-defined module named system.

System module

The System module imports several separate modules, and their documentation is in separate files:

Here is a short overview of the most commonly used functions from the system module. Function names in the tables below are clickable and will take you to the full documentation of the function.

There are many more functions available than the ones listed in this overview. Use the table of contents on the left-hand side and/or Ctrl+F to navigate through this module.

Strings and characters

ProcUsage
len(s)Return the length of a string
chr(i)Convert an int in the range 0..255 to a character
ord(c)Return int value of a character
a & bConcatenate two strings
s.add(c)Add character to the string
$Convert various types to string

See also:

  • strutils module for common string functions
  • strformat module for string interpolation and formatting
  • unicode module for Unicode UTF-8 handling
  • strscans for scanf and scanp macros, which offer easier substring extraction than regular expressions
  • strtabs module for efficient hash tables (dictionaries, in some programming languages) mapping from strings to strings

Seqs

ProcUsage
newSeqCreate a new sequence of a given length
newSeqOfCapCreate a new sequence with zero length and a given capacity
setLenSet the length of a sequence
lenReturn the length of a sequence
@Turn an array into a sequence
addAdd an item to the sequence
insertInsert an item at a specific position
deleteDelete an item while preserving the order of elements (O(n) operation)
delO(1) removal, doesn't preserve the order
popRemove and return last item of a sequence
x & yConcatenate two sequences
x[a .. b]Slice of a sequence (both ends included)
x[a .. ^b]Slice of a sequence but b is a reversed index (both ends included)
x[a ..< b]Slice of a sequence (excluded upper bound)

See also:

Sets

Built-in bit sets.

ProcUsage
inclInclude element y in the set x
exclExclude element y from the set x
cardReturn the cardinality of the set, i.e. the number of elements
a * bIntersection
a + bUnion
a - bDifference
containsCheck if an element is in the set
a < bCheck if a is a subset of b

See also:

Numbers

ProcUsage Also known as (in other languages)
divInteger division//
modInteger modulo (remainder)%
shlShift left<<
shrShift right>>
ashrArithmetic shift right
andBitwise and&
orBitwise or|
xorBitwise xor^
notBitwise not (complement)~
toIntConvert floating-point number into an int
toFloatConvert an integer into a float

See also:

Ordinals

Ordinal type includes integer, bool, character, and enumeration types, as well as their subtypes.

ProcUsage
succSuccessor of the value
predPredecessor of the value
incIncrement the ordinal
decDecrement the ordinal
highReturn the highest possible value
lowReturn the lowest possible value
ordReturn int value of an ordinal value

Misc

ProcUsage
isCheck if two arguments are of the same type
isnotNegated version of is
!=Not equals
addrTake the address of a memory location
T and FBoolean and
T or FBoolean or
T xor FBoolean xor (exclusive or)
not TBoolean not
a[^x]Take the element at the reversed index x
a .. bBinary slice that constructs an interval [a, b]
a ..^ bInterval [a, b] but b as reversed index
a ..< bInterval [a, b) (excluded upper bound)
runnableExamplesCreate testable documentation

Types

AccessViolationDefect = object of Defect
Raised for invalid memory access errors Source   Edit  
AccessViolationError {....deprecated: "See corresponding Defect".} = AccessViolationDefect
Deprecated: See corresponding Defect
Source   Edit  
AllocStats = object
  allocCount: int
  deallocCount: int
Source   Edit  
any {....deprecated: "Deprecated since v1.5; Use auto instead.".} = distinct auto
Deprecated: Deprecated since v1.5; Use auto instead.
Deprecated; Use auto instead. See https://github.com/nim-lang/RFCs/issues/281 Source   Edit  
ArithmeticDefect = object of Defect
Raised if any kind of arithmetic error occurred. Source   Edit  
ArithmeticError {....deprecated: "See corresponding Defect".} = ArithmeticDefect
Deprecated: See corresponding Defect
Source   Edit  
array[I; T] {.magic: "Array".}
Generic type to construct fixed-length arrays. Source   Edit  
AssertionDefect = object of Defect

Raised when assertion is proved wrong.

Usually the result of using the assert() template.

Source   Edit  
AssertionError {....deprecated: "See corresponding Defect".} = AssertionDefect
Deprecated: See corresponding Defect
Source   Edit  
AtomType = SomeNumber | pointer | ptr | char | bool
Type Class representing valid types for use with atomic procs Source   Edit  
auto {.magic: Expr.}
Meta type for automatic type determination. Source   Edit  
BackwardsIndex = distinct int
Type that is constructed by ^ for reversed array accesses. (See ^ template) Source   Edit  
BiggestFloat = float64
is an alias for the biggest floating point type the Nim compiler supports. Currently this is float64, but it is platform-dependent in general. Source   Edit  
BiggestInt = int64
is an alias for the biggest signed integer type the Nim compiler supports. Currently this is int64, but it is platform-dependent in general. Source   Edit  
BiggestUInt = uint64
is an alias for the biggest unsigned integer type the Nim compiler supports. Currently this is uint32 for JS and uint64 for other targets. Source   Edit  
bool {.magic: "Bool".} = enum
  false = 0, true = 1
Built-in boolean type. Source   Edit  
byte = uint8
This is an alias for uint8, that is an unsigned integer, 8 bits wide. Source   Edit  
ByteAddress = int
is the signed integer type that should be used for converting pointers to integer addresses for readability. Source   Edit  
CatchableError = object of Exception
Abstract class for all exceptions that are catchable. Source   Edit  
cchar {.importc: "char", nodecl.} = char
This is the same as the type char in C. Source   Edit  
cdouble {.importc: "double", nodecl.} = float64
This is the same as the type double in C. Source   Edit  
cfloat {.importc: "float", nodecl.} = float32
This is the same as the type float in C. Source   Edit  
char {.magic: Char.}
Built-in 8 bit character type (unsigned). Source   Edit  
cint {.importc: "int", nodecl.} = int32
This is the same as the type int in C. Source   Edit  
clong {.importc: "long", nodecl.} = int
This is the same as the type long in C. Source   Edit  
clongdouble {.importc: "long double", nodecl.} = BiggestFloat
This is the same as the type long double in C. This C type is not supported by Nim's code generator. Source   Edit  
clonglong {.importc: "long long", nodecl.} = int64
This is the same as the type long long in C. Source   Edit  
cschar {.importc: "signed char", nodecl.} = int8
This is the same as the type signed char in C. Source   Edit  
cshort {.importc: "short", nodecl.} = int16
This is the same as the type short in C. Source   Edit  
csize {.importc: "size_t", nodecl, ...deprecated: "use `csize_t` instead".} = int
Deprecated: use `csize_t` instead
This isn't the same as size_t in C. Don't use it. Source   Edit  
csize_t {.importc: "size_t", nodecl.} = uint
This is the same as the type size_t in C. Source   Edit  
cstring {.magic: Cstring.}
Built-in cstring (compatible string) type. Source   Edit  
cstringArray {.importc: "char**", nodecl.} = ptr UncheckedArray[cstring]
This is binary compatible to the type char** in C. The array's high value is large enough to disable bounds checking in practice. Use cstringArrayToSeq proc to convert it into a seq[string]. Source   Edit  
cuchar {.importc: "unsigned char", nodecl,
         ...deprecated: "use `char` or `uint8` instead".} = char
Deprecated: use `char` or `uint8` instead
Deprecated: Use uint8 instead. Source   Edit  
cuint {.importc: "unsigned int", nodecl.} = uint32
This is the same as the type unsigned int in C. Source   Edit  
culong {.importc: "unsigned long", nodecl.} = uint
This is the same as the type unsigned long in C. Source   Edit  
culonglong {.importc: "unsigned long long", nodecl.} = uint64
This is the same as the type unsigned long long in C. Source   Edit  
cushort {.importc: "unsigned short", nodecl.} = uint16
This is the same as the type unsigned short in C. Source   Edit  
DeadThreadDefect = object of Defect
Raised if it is attempted to send a message to a dead thread. Source   Edit  
DeadThreadError {....deprecated: "See corresponding Defect".} = DeadThreadDefect
Deprecated: See corresponding Defect
Source   Edit  
Defect = object of Exception
Abstract base class for all exceptions that Nim's runtime raises but that are strictly uncatchable as they can also be mapped to a quit / trap / exit operation. Source   Edit  
DivByZeroDefect = object of ArithmeticDefect
Raised for runtime integer divide-by-zero errors. Source   Edit  
DivByZeroError {....deprecated: "See corresponding Defect".} = DivByZeroDefect
Deprecated: See corresponding Defect
Source   Edit  
Endianness = enum
  littleEndian, bigEndian
Type describing the endianness of a processor. Source   Edit  
EOFError = object of IOError
Raised if an IO "end of file" error occurred. Source   Edit  
Exception {.compilerproc, magic: "Exception".} = object of RootObj
  parent*: ref Exception     ## Parent exception (can be used as a stack).
  name*: cstring             ## The exception's name is its Nim identifier.
                             ## This field is filled automatically in the
                             ## `raise` statement.
  msg* {.exportc: "message".}: string ## The exception's message. Not
                                      ## providing an exception message
                                      ## is bad style.
  when defined(js):
      trace: string

  else:
      trace: seq[StackTraceEntry]

  up: ref Exception

Base exception class.

Each exception has to inherit from Exception. See the full exception hierarchy.

Source   Edit  
ExecIOEffect = object of IOEffect
Effect describing an executing IO operation. Source   Edit  
FieldDefect = object of Defect
Raised if a record field is not accessible because its discriminant's value does not fit. Source   Edit  
FieldError {....deprecated: "See corresponding Defect".} = FieldDefect
Deprecated: See corresponding Defect
Source   Edit  
FileSeekPos = enum
  fspSet,                   ## Seek to absolute value
  fspCur,                   ## Seek relative to current position
  fspEnd                     ## Seek relative to end
Position relative to which seek should happen. Source   Edit  
float {.magic: Float.}
Default floating point type. Source   Edit  
float32 {.magic: Float32.}
32 bit floating point type. Source   Edit  
float64 {.magic: Float.}
64 bit floating point type. Source   Edit  
FloatDivByZeroDefect = object of FloatingPointDefect

Raised by division by zero.

Divisor is zero and dividend is a finite nonzero number.

Source   Edit  
FloatDivByZeroError {....deprecated: "See corresponding Defect".} = FloatDivByZeroDefect
Deprecated: See corresponding Defect
Source   Edit  
FloatInexactDefect = object of FloatingPointDefect

Raised for inexact results.

The operation produced a result that cannot be represented with infinite precision -- for example: 2.0 / 3.0, log(1.1)

Note: Nim currently does not detect these!

Source   Edit  
FloatInexactError {....deprecated: "See corresponding Defect".} = FloatInexactDefect
Deprecated: See corresponding Defect
Source   Edit  
FloatingPointDefect = object of Defect
Base class for floating point exceptions. Source   Edit  
FloatingPointError {....deprecated: "See corresponding Defect".} = FloatingPointDefect
Deprecated: See corresponding Defect
Source   Edit  
FloatInvalidOpDefect = object of FloatingPointDefect

Raised by invalid operations according to IEEE.

Raised by 0.0/0.0, for example.

Source   Edit  
FloatInvalidOpError {....deprecated: "See corresponding Defect".} = FloatInvalidOpDefect
Deprecated: See corresponding Defect
Source   Edit  
FloatOverflowDefect = object of FloatingPointDefect

Raised for overflows.

The operation produced a result that exceeds the range of the exponent.

Source   Edit  
FloatOverflowError {....deprecated: "See corresponding Defect".} = FloatOverflowDefect
Deprecated: See corresponding Defect
Source   Edit  
FloatUnderflowDefect = object of FloatingPointDefect

Raised for underflows.

The operation produced a result that is too small to be represented as a normal number.

Source   Edit  
FloatUnderflowError {....deprecated: "See corresponding Defect".} = FloatUnderflowDefect
Deprecated: See corresponding Defect
Source   Edit  
ForeignCell = object
  data*: pointer
  owner: ptr GcHeap
Source   Edit  
ForLoopStmt {.compilerproc.} = object
A special type that marks a macro as a for-loop macro. See "For Loop Macro". Source   Edit  
GC_Strategy = enum
  gcThroughput,             ## optimize for throughput
  gcResponsiveness,         ## optimize for responsiveness (default)
  gcOptimizeTime,           ## optimize for speed
  gcOptimizeSpace            ## optimize for memory footprint
The strategy the GC should use for the application. Source   Edit  
HSlice[T; U] = object
  a*: T                      ## The lower bound (inclusive).
  b*: U                      ## The upper bound (inclusive).
  
"Heterogeneous" slice type. Source   Edit  
IndexDefect = object of Defect
Raised if an array index is out of bounds. Source   Edit  
IndexError {....deprecated: "See corresponding Defect".} = IndexDefect
Deprecated: See corresponding Defect
Source   Edit  
int {.magic: "Int".}
Default integer type; bitwidth depends on architecture, but is always the same as a pointer. Source   Edit  
int8 {.magic: "Int8".}
Signed 8 bit integer type. Source   Edit  
int16 {.magic: "Int16".}
Signed 16 bit integer type. Source   Edit  
int32 {.magic: "Int32".}
Signed 32 bit integer type. Source   Edit  
int64 {.magic: "Int64".}
Signed 64 bit integer type. Source   Edit  
IOEffect = object of RootEffect
IO effect. Source   Edit  
IOError = object of CatchableError
Raised if an IO error occurred. Source   Edit  
iterable[T] {.magic: IterableType.}
Represents an expression that yields T Source   Edit  
JsRoot = ref object of RootObj
  
Root type of the JavaScript object hierarchy Source   Edit  
KeyError = object of ValueError

Raised if a key cannot be found in a table.

Mostly used by the tables module, it can also be raised by other collection modules like sets or strtabs.

Source   Edit  
lent[T] {.magic: "BuiltinType".}
Source   Edit  
LibraryError = object of OSError
Raised if a dynamic library could not be loaded. Source   Edit  
Natural = range[0 .. high(int)]
is an int type ranging from zero to the maximum value of an int. This type is often useful for documentation and debugging. Source   Edit  
NilAccessDefect = object of Defect

Raised on dereferences of nil pointers.

This is only raised if the segfaults module was imported!

Source   Edit  
NilAccessError {....deprecated: "See corresponding Defect".} = NilAccessDefect
Deprecated: See corresponding Defect
Source   Edit  
NimNode {.magic: "PNimrodNode".} = ref NimNodeObj
Represents a Nim AST node. Macros operate on this type. Source   Edit  
ObjectAssignmentDefect = object of Defect
Raised if an object gets assigned to its parent's object. Source   Edit  
ObjectAssignmentError {....deprecated: "See corresponding Defect".} = ObjectAssignmentDefect
Deprecated: See corresponding Defect
Source   Edit  
ObjectConversionDefect = object of Defect
Raised if an object is converted to an incompatible object type. You can use of operator to check if conversion will succeed. Source   Edit  
ObjectConversionError {....deprecated: "See corresponding Defect".} = ObjectConversionDefect
Deprecated: See corresponding Defect
Source   Edit  
openArray[T] {.magic: "OpenArray".}
Generic type to construct open arrays. Open arrays are implemented as a pointer to the array data and a length field. Source   Edit  
Ordinal[T] {.magic: Ordinal.}
Generic ordinal type. Includes integer, bool, character, and enumeration types as well as their subtypes. See also SomeOrdinal. Source   Edit  
OSError = object of CatchableError
  errorCode*: int32          ## OS-defined error code describing this error.
  
Raised if an operating system service failed. Source   Edit  
OutOfMemDefect = object of Defect
Raised for unsuccessful attempts to allocate memory. Source   Edit  
OutOfMemError {....deprecated: "See corresponding Defect".} = OutOfMemDefect
Deprecated: See corresponding Defect
Source   Edit  
OverflowDefect = object of ArithmeticDefect

Raised for runtime integer overflows.

This happens for calculations whose results are too large to fit in the provided bits.

Source   Edit  
OverflowError {....deprecated: "See corresponding Defect".} = OverflowDefect
Deprecated: See corresponding Defect
Source   Edit  
owned[T] {.magic: "BuiltinType".}
type constructor to mark a ref/ptr or a closure as owned. Source   Edit  
PFloat32 = ptr float32
An alias for ptr float32. Source   Edit  
PFloat64 = ptr float64
An alias for ptr float64. Source   Edit  
PFrame = ptr TFrame
Represents a runtime frame of the call stack; part of the debugger API. Source   Edit  
PInt32 = ptr int32
An alias for ptr int32. Source   Edit  
PInt64 = ptr int64
An alias for ptr int64. Source   Edit  
pointer {.magic: Pointer.}
Built-in pointer type, use the addr operator to get a pointer to a variable. Source   Edit  
Positive = range[1 .. high(int)]
is an int type ranging from one to the maximum value of an int. This type is often useful for documentation and debugging. Source   Edit  
ptr[T] {.magic: Pointer.}
Built-in generic untraced pointer type. Source   Edit  
range[T] {.magic: "Range".}
Generic type to construct range types. Source   Edit  
RangeDefect = object of Defect
Raised if a range check error occurred. Source   Edit  
RangeError {....deprecated: "See corresponding Defect".} = RangeDefect
Deprecated: See corresponding Defect
Source   Edit  
ReadIOEffect = object of IOEffect
Effect describing a read IO operation. Source   Edit  
ref[T] {.magic: Pointer.}
Built-in generic traced pointer type. Source   Edit  
ReraiseDefect = object of Defect
Raised if there is no exception to reraise. Source   Edit  
ReraiseError {....deprecated: "See corresponding Defect".} = ReraiseDefect
Deprecated: See corresponding Defect
Source   Edit  
ResourceExhaustedError = object of CatchableError
Raised if a resource request could not be fulfilled. Source   Edit  
RootEffect {.compilerproc.} = object of RootObj

Base effect class.

Each effect should inherit from RootEffect unless you know what you're doing.

Source   Edit  
RootObj {.compilerproc, inheritable.} = object

The root of Nim's object hierarchy.

Objects should inherit from RootObj or one of its descendants. However, objects that have no ancestor are also allowed.

Source   Edit  
RootRef = ref RootObj
Reference to RootObj. Source   Edit  
seq[T] {.magic: "Seq".}
Generic type to construct sequences. Source   Edit  
set[T] {.magic: "Set".}
Generic type to construct bit sets. Source   Edit  
sink[T] {.magic: "BuiltinType".}
Source   Edit  
Slice[T] = HSlice[T, T]
An alias for HSlice[T, T]. Source   Edit  
SomeFloat = float | float32 | float64
Type class matching all floating point number types. Source   Edit  
SomeInteger = SomeSignedInt | SomeUnsignedInt
Type class matching all integer types. Source   Edit  
SomeNumber = SomeInteger | SomeFloat
Type class matching all number types. Source   Edit  
SomeOrdinal = int | int8 | int16 | int32 | int64 | bool | enum | uint | uint8 |
    uint16 |
    uint32 |
    uint64
Type class matching all ordinal types; however this includes enums with holes. See also Ordinal Source   Edit  
SomeSignedInt = int | int8 | int16 | int32 | int64
Type class matching all signed integer types. Source   Edit  
SomeUnsignedInt = uint | uint8 | uint16 | uint32 | uint64
Type class matching all unsigned integer types. Source   Edit  
StackOverflowDefect = object of Defect
Raised if the hardware stack used for subroutine calls overflowed. Source   Edit  
StackOverflowError {....deprecated: "See corresponding Defect".} = StackOverflowDefect
Deprecated: See corresponding Defect
Source   Edit  
StackTraceEntry = object
  procname*: cstring         ## Name of the proc that is currently executing.
  line*: int                 ## Line number of the proc that is currently executing.
  filename*: cstring         ## Filename of the proc that is currently executing.
  when NimStackTraceMsgs:
      frameMsg*: string ## When a stacktrace is generated in a given frame and
                        ## rendered at a later time, we should ensure the stacktrace
                        ## data isn't invalidated; any pointer into PFrame is
                        ## subject to being invalidated so shouldn't be stored.
    
  when defined(nimStackTraceOverride):
      programCounter*: uint ## Program counter - will be used to get the rest of the info,
                            ## when `$` is called on this type. We can't use
                            ## "cuintptr_t" in here.
      procnameStr*, filenameStr*: string ## GC-ed alternatives to "procname" and "filename"
    
  
In debug mode exceptions store the stack trace that led to them. A StackTraceEntry is a single entry of the stack trace. Source   Edit  
static[T] {.magic: "Static".}

Meta type representing all values that can be evaluated at compile-time.

The type coercion static(x) can be used to force the compile-time evaluation of the given expression x.

Source   Edit  
string {.magic: String.}
Built-in string type. Source   Edit  
TaintedString {....deprecated: "Deprecated since 1.5".} = string
Deprecated: Deprecated since 1.5
Source   Edit  
TFrame {.importc, nodecl, final.} = object
  prev*: PFrame              ## Previous frame; used for chaining the call stack.
  procname*: cstring         ## Name of the proc that is currently executing.
  line*: int                 ## Line number of the proc that is currently executing.
  filename*: cstring         ## Filename of the proc that is currently executing.
  len*: int16                ## Length of the inspectable slots.
  calldepth*: int16          ## Used for max call depth checking.
  when NimStackTraceMsgs:
      frameMsgLen*: int      ## end position in frameMsgBuf for this frame.
    
  
The frame itself. Source   Edit  
TimeEffect = object of RootEffect
Time effect. Source   Edit  
type[T] {.magic: "Type".}

Meta type representing the type of all type values.

The coercion type(x) can be used to obtain the type of the given expression x.

Source   Edit  
typed {.magic: Stmt.}
Meta type to denote an expression that is resolved (for templates). Source   Edit  
typedesc {.magic: TypeDesc.}
Meta type to denote a type description. Source   Edit  
TypeOfMode = enum
  typeOfProc,               ## Prefer the interpretation that means `x` is a proc call.
  typeOfIter                 ## Prefer the interpretation that means `x` is an iterator call.
Possible modes of typeof. Source   Edit  
uint {.magic: "UInt".}
Unsigned default integer type. Source   Edit  
uint8 {.magic: "UInt8".}
Unsigned 8 bit integer type. Source   Edit  
uint16 {.magic: "UInt16".}
Unsigned 16 bit integer type. Source   Edit  
uint32 {.magic: "UInt32".}
Unsigned 32 bit integer type. Source   Edit  
uint64 {.magic: "UInt64".}
Unsigned 64 bit integer type. Source   Edit  
UncheckedArray[T] {.magic: "UncheckedArray".}
Source   Edit  
untyped {.magic: Expr.}
Meta type to denote an expression that is not resolved (for templates). Source   Edit  
ValueError = object of CatchableError
Raised for string and object conversion errors. Source   Edit  
varargs[T] {.magic: "Varargs".}
Generic type to construct a varargs type. Source   Edit  
void {.magic: "VoidType".}
Meta type to denote the absence of any type. Source   Edit  
WriteIOEffect = object of IOEffect
Effect describing a write IO operation. Source   Edit  

Vars

errorMessageWriter: (proc (msg: string) {....tags: [WriteIOEffect], gcsafe,
    locks: 0, nimcall.})
Function that will be called instead of stdmsg.write when printing stacktrace. Unstable API. Source   Edit  
globalRaiseHook: proc (e: ref Exception): bool {.nimcall, ...gcsafe, locks: 0.}
With this hook you can influence exception handling on a global level. If not nil, every 'raise' statement ends up calling this hook.
Warning: Ordinary application code should never set this hook! You better know what you do when setting this.

If globalRaiseHook returns false, the exception is caught and does not propagate further through the call stack.

Source   Edit  
localRaiseHook: proc (e: ref Exception): bool {.nimcall, ...gcsafe, locks: 0.}
With this hook you can influence exception handling on a thread local level. If not nil, every 'raise' statement ends up calling this hook.
Warning: Ordinary application code should never set this hook! You better know what you do when setting this.

If localRaiseHook returns false, the exception is caught and does not propagate further through the call stack.

Source   Edit  
onUnhandledException: (proc (errorMsg: string) {.nimcall, ...gcsafe.})

Set this error handler to override the existing behaviour on an unhandled exception.

The default is to write a stacktrace to stderr and then call quit(1). Unstable API.

Source   Edit  
outOfMemHook: proc () {.nimcall, ...tags: [], gcsafe, locks: 0, ...raises: [].}

Set this variable to provide a procedure that should be called in case of an out of memory event. The standard handler writes an error message and terminates the program.

outOfMemHook can be used to raise an exception in case of OOM like so:

var gOutOfMem: ref EOutOfMemory
new(gOutOfMem) # need to be allocated *before* OOM really happened!
gOutOfMem.msg = "out of memory"

proc handleOOM() =
  raise gOutOfMem

system.outOfMemHook = handleOOM

If the handler does not raise an exception, ordinary control flow continues and the program is terminated.

Source   Edit  
programResult: int
deprecated, prefer quit or exitprocs.getProgramResult, exitprocs.setProgramResult. Source   Edit  
unhandledExceptionHook: proc (e: ref Exception) {.nimcall, ...tags: [], gcsafe,
    locks: 0, ...raises: [].}
Set this variable to provide a procedure that should be called in case of an unhandle exception event. The standard handler writes an error message and terminates the program, except when using --os:any Source   Edit  

Lets

nimvm: bool = false
May be used only in when expression. It is true in Nim VM context and false otherwise. Source   Edit  

Consts

appType: string = ""
A string that describes the application type. Possible values: "console", "gui", "lib". Source   Edit  
CompileDate: string = "0000-00-00"
The date (in UTC) of compilation as a string of the form YYYY-MM-DD. This works thanks to compiler magic. Source   Edit  
CompileTime: string = "00:00:00"
The time (in UTC) of compilation as a string of the form HH:MM:SS. This works thanks to compiler magic. Source   Edit  
cpuEndian: Endianness = littleEndian
The endianness of the target CPU. This is a valuable piece of information for low-level code only. This works thanks to compiler magic. Source   Edit  
hostCPU: string = ""

A string that describes the host CPU.

Possible values: "i386", "alpha", "powerpc", "powerpc64", "powerpc64el", "sparc", "amd64", "mips", "mipsel", "arm", "arm64", "mips64", "mips64el", "riscv32", "riscv64", '"loongarch64"'.

Source   Edit  
hostOS: string = ""

A string that describes the host operating system.

Possible values: "windows", "macosx", "linux", "netbsd", "freebsd", "openbsd", "solaris", "aix", "haiku", "standalone".

Source   Edit  
Inf = 0x7FF0000000000000'f64
Contains the IEEE floating point value of positive infinity. Source   Edit  
isMainModule: bool = false
True only when accessed in the main module. This works thanks to compiler magic. It is useful to embed testing code in a module. Source   Edit  
NaN = 0x7FF7FFFFFFFFFFFF'f64

Contains an IEEE floating point value of Not A Number.

Note that you cannot compare a floating point value to this value and expect a reasonable result - use the isNaN or classify procedure in the math module for checking for NaN.

Source   Edit  
NegInf = 0xFFF0000000000000'f64
Contains the IEEE floating point value of negative infinity. Source   Edit  
NimMajor: int = 1
is the major number of Nim's version. Example:
when (NimMajor, NimMinor, NimPatch) >= (1, 3, 1): discard
Source   Edit  
NimMinor: int = 7
is the minor number of Nim's version. Odd for devel, even for releases. Source   Edit  
NimPatch: int = 1
is the patch number of Nim's version. Odd for devel, even for releases. Source   Edit  
NimVersion: string = "1.7.1"
is the version of Nim as a string. Source   Edit  
off = false
Alias for false. Source   Edit  
on = true
Alias for true. Source   Edit  
QuitFailure = 1
is the value that should be passed to quit to indicate failure. Source   Edit  
QuitSuccess = 0
is the value that should be passed to quit to indicate success. Source   Edit  

Procs

proc `%%`(x, y: int): int {.inline, ...raises: [], tags: [].}

Treats x and y as unsigned and compute the modulo of x and y.

The result is truncated to fit into the result. This implements modulo arithmetic. No overflow errors are possible.

Source   Edit  
proc `%%`(x, y: int8): int8 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `%%`(x, y: int16): int16 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `%%`(x, y: int32): int32 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `%%`(x, y: int64): int64 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `&`(x, y: char): string {.magic: "ConStrStr", noSideEffect, merge,
                               ...raises: [], tags: [].}
Concatenates characters x and y into a string.
assert('a' & 'b' == "ab")
Source   Edit  
proc `&`(x, y: string): string {.magic: "ConStrStr", noSideEffect, merge,
                                 ...raises: [], tags: [].}
Concatenates strings x and y.
assert("ab" & "cd" == "abcd")
Source   Edit  
proc `&`(x: char; y: string): string {.magic: "ConStrStr", noSideEffect, merge,
                                       ...raises: [], tags: [].}
Concatenates x with y.
assert('a' & "bc" == "abc")
Source   Edit  
proc `&`(x: string; y: char): string {.magic: "ConStrStr", noSideEffect, merge,
                                       ...raises: [], tags: [].}
Concatenates x with y.
assert("ab" & 'c' == "abc")
Source   Edit  
proc `&`[T](x, y: seq[T]): seq[T] {.noSideEffect.}

Concatenates two sequences.

Requires copying of the sequences.

See also:

assert(@[1, 2, 3, 4] & @[5, 6] == @[1, 2, 3, 4, 5, 6])
Source   Edit  
proc `&`[T](x: seq[T]; y: T): seq[T] {.noSideEffect.}

Appends element y to the end of the sequence.

Requires copying of the sequence.

See also:

assert(@[1, 2, 3] & 4 == @[1, 2, 3, 4])
Source   Edit  
proc `&`[T](x: T; y: seq[T]): seq[T] {.noSideEffect.}

Prepends the element x to the beginning of the sequence.

Requires copying of the sequence.

assert(1 & @[2, 3, 4] == @[1, 2, 3, 4])
Source   Edit  
proc `&=`(x: var string; y: string) {.magic: "AppendStrStr", noSideEffect,
                                      ...raises: [], tags: [].}
Appends in place to a string.
var a = "abc"
a &= "de" # a <- "abcde"
Source   Edit  
proc `*`(x, y: float): float {.magic: "MulF64", noSideEffect, ...raises: [],
                               tags: [].}
Source   Edit  
proc `*`(x, y: float32): float32 {.magic: "MulF64", noSideEffect, ...raises: [],
                                   tags: [].}
Source   Edit  
proc `*`(x, y: int): int {.magic: "MulI", noSideEffect, ...raises: [], tags: [].}
Binary * operator for an integer. Source   Edit  
proc `*`(x, y: int8): int8 {.magic: "MulI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `*`(x, y: int16): int16 {.magic: "MulI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `*`(x, y: int32): int32 {.magic: "MulI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `*`(x, y: int64): int64 {.magic: "MulI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `*`(x, y: uint): uint {.magic: "MulU", noSideEffect, ...raises: [], tags: [].}
Binary * operator for unsigned integers. Source   Edit  
proc `*`(x, y: uint8): uint8 {.magic: "MulU", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `*`(x, y: uint16): uint16 {.magic: "MulU", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `*`(x, y: uint32): uint32 {.magic: "MulU", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `*`(x, y: uint64): uint64 {.magic: "MulU", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
func `*`[T](x, y: set[T]): set[T] {.magic: "MulSet", ...raises: [], tags: [].}
This operator computes the intersection of two sets.

Example:

assert {1, 2, 3} * {2, 3, 4} == {2, 3}
Source   Edit  
proc `*%`(x, y: int): int {.inline, ...raises: [], tags: [].}

Treats x and y as unsigned and multiplies them.

The result is truncated to fit into the result. This implements modulo arithmetic. No overflow errors are possible.

Source   Edit  
proc `*%`(x, y: int8): int8 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `*%`(x, y: int16): int16 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `*%`(x, y: int32): int32 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `*%`(x, y: int64): int64 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `*=`[T: float | float32 | float64](x: var T; y: T) {.inline, noSideEffect.}
Multiplies in place a floating point number. Source   Edit  
proc `*=`[T: SomeInteger](x: var T; y: T) {.inline, noSideEffect.}
Binary *= operator for integers. Source   Edit  
proc `+`(x, y: float): float {.magic: "AddF64", noSideEffect, ...raises: [],
                               tags: [].}
Source   Edit  
proc `+`(x, y: float32): float32 {.magic: "AddF64", noSideEffect, ...raises: [],
                                   tags: [].}
Source   Edit  
proc `+`(x, y: int): int {.magic: "AddI", noSideEffect, ...raises: [], tags: [].}
Binary + operator for an integer. Source   Edit  
proc `+`(x, y: int8): int8 {.magic: "AddI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `+`(x, y: int16): int16 {.magic: "AddI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `+`(x, y: int32): int32 {.magic: "AddI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `+`(x, y: int64): int64 {.magic: "AddI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `+`(x, y: uint): uint {.magic: "AddU", noSideEffect, ...raises: [], tags: [].}
Binary + operator for unsigned integers. Source   Edit  
proc `+`(x, y: uint8): uint8 {.magic: "AddU", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `+`(x, y: uint16): uint16 {.magic: "AddU", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `+`(x, y: uint32): uint32 {.magic: "AddU", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `+`(x, y: uint64): uint64 {.magic: "AddU", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `+`(x: float): float {.magic: "UnaryPlusF64", noSideEffect, ...raises: [],
                            tags: [].}
Source   Edit  
proc `+`(x: float32): float32 {.magic: "UnaryPlusF64", noSideEffect, ...raises: [],
                                tags: [].}
Source   Edit  
proc `+`(x: int): int {.magic: "UnaryPlusI", noSideEffect, ...raises: [], tags: [].}
Unary + operator for an integer. Has no effect. Source   Edit  
proc `+`(x: int8): int8 {.magic: "UnaryPlusI", noSideEffect, ...raises: [],
                          tags: [].}
Source   Edit  
proc `+`(x: int16): int16 {.magic: "UnaryPlusI", noSideEffect, ...raises: [],
                            tags: [].}
Source   Edit  
proc `+`(x: int32): int32 {.magic: "UnaryPlusI", noSideEffect, ...raises: [],
                            tags: [].}
Source   Edit  
proc `+`(x: int64): int64 {.magic: "UnaryPlusI", noSideEffect, ...raises: [],
                            tags: [].}
Source   Edit  
func `+`[T](x, y: set[T]): set[T] {.magic: "PlusSet", ...raises: [], tags: [].}
This operator computes the union of two sets.

Example:

assert {1, 2, 3} + {2, 3, 4} == {1, 2, 3, 4}
Source   Edit  
proc `+%`(x, y: int): int {.inline, ...raises: [], tags: [].}

Treats x and y as unsigned and adds them.

The result is truncated to fit into the result. This implements modulo arithmetic. No overflow errors are possible.

Source   Edit  
proc `+%`(x, y: int8): int8 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `+%`(x, y: int16): int16 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `+%`(x, y: int32): int32 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `+%`(x, y: int64): int64 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `+=`[T: float | float32 | float64](x: var T; y: T) {.inline, noSideEffect.}
Increments in place a floating point number. Source   Edit  
proc `+=`[T: SomeInteger](x: var T; y: T) {.magic: "Inc", noSideEffect,
    ...raises: [], tags: [].}
Increments an integer. Source   Edit  
proc `-`(a, b: AllocStats): AllocStats {....raises: [], tags: [].}
Source   Edit  
proc `-`(x, y: float): float {.magic: "SubF64", noSideEffect, ...raises: [],
                               tags: [].}
Source   Edit  
proc `-`(x, y: float32): float32 {.magic: "SubF64", noSideEffect, ...raises: [],
                                   tags: [].}
Source   Edit  
proc `-`(x, y: int): int {.magic: "SubI", noSideEffect, ...raises: [], tags: [].}
Binary - operator for an integer. Source   Edit  
proc `-`(x, y: int8): int8 {.magic: "SubI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `-`(x, y: int16): int16 {.magic: "SubI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `-`(x, y: int32): int32 {.magic: "SubI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `-`(x, y: int64): int64 {.magic: "SubI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `-`(x, y: uint): uint {.magic: "SubU", noSideEffect, ...raises: [], tags: [].}
Binary - operator for unsigned integers. Source   Edit  
proc `-`(x, y: uint8): uint8 {.magic: "SubU", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `-`(x, y: uint16): uint16 {.magic: "SubU", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `-`(x, y: uint32): uint32 {.magic: "SubU", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `-`(x, y: uint64): uint64 {.magic: "SubU", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `-`(x: float): float {.magic: "UnaryMinusF64", noSideEffect, ...raises: [],
                            tags: [].}
Source   Edit  
proc `-`(x: float32): float32 {.magic: "UnaryMinusF64", noSideEffect,
                                ...raises: [], tags: [].}
Source   Edit  
proc `-`(x: int): int {.magic: "UnaryMinusI", noSideEffect, ...raises: [], tags: [].}
Unary - operator for an integer. Negates x. Source   Edit  
proc `-`(x: int8): int8 {.magic: "UnaryMinusI", noSideEffect, ...raises: [],
                          tags: [].}
Source   Edit  
proc `-`(x: int16): int16 {.magic: "UnaryMinusI", noSideEffect, ...raises: [],
                            tags: [].}
Source   Edit  
proc `-`(x: int32): int32 {.magic: "UnaryMinusI", noSideEffect, ...raises: [],
                            tags: [].}
Source   Edit  
proc `-`(x: int64): int64 {.magic: "UnaryMinusI64", noSideEffect, ...raises: [],
                            tags: [].}
Source   Edit  
func `-`[T](x, y: set[T]): set[T] {.magic: "MinusSet", ...raises: [], tags: [].}
This operator computes the difference of two sets.

Example:

assert {1, 2, 3} - {2, 3, 4} == {1}
Source   Edit  
proc `-%`(x, y: int): int {.inline, ...raises: [], tags: [].}

Treats x and y as unsigned and subtracts them.

The result is truncated to fit into the result. This implements modulo arithmetic. No overflow errors are possible.

Source   Edit  
proc `-%`(x, y: int8): int8 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `-%`(x, y: int16): int16 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `-%`(x, y: int32): int32 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `-%`(x, y: int64): int64 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `-=`[T: float | float32 | float64](x: var T; y: T) {.inline, noSideEffect.}
Decrements in place a floating point number. Source   Edit  
proc `-=`[T: SomeInteger](x: var T; y: T) {.magic: "Dec", noSideEffect,
    ...raises: [], tags: [].}
Decrements an integer. Source   Edit  
proc `..`[T, U](a: sink T; b: sink U): HSlice[T, U] {.noSideEffect, inline,
    magic: "DotDot", ...raises: [], tags: [].}

Binary slice operator that constructs an interval [a, b], both a and b are inclusive.

Slices can also be used in the set constructor and in ordinal case statements, but then they are special-cased by the compiler.

let a = [10, 20, 30, 40, 50]
echo a[2 .. 3] # @[30, 40]
Source   Edit  
proc `..`[T](b: sink T): HSlice[int, T] {.noSideEffect, inline, magic: "DotDot",
    ...deprecated: "replace `..b` with `0..b`", raises: [], tags: [].}
Deprecated: replace `..b` with `0..b`
Unary slice operator that constructs an interval [default(int), b].
let a = [10, 20, 30, 40, 50]
echo a[.. 2] # @[10, 20, 30]
Source   Edit  
proc `/`(x, y: float): float {.magic: "DivF64", noSideEffect, ...raises: [],
                               tags: [].}
Source   Edit  
proc `/`(x, y: float32): float32 {.magic: "DivF64", noSideEffect, ...raises: [],
                                   tags: [].}
Source   Edit  
proc `/`(x, y: int): float {.inline, noSideEffect, ...raises: [], tags: [].}

Division of integers that results in a float.

See also:

echo 7 / 5 # => 1.4
Source   Edit  
proc `/%`(x, y: int): int {.inline, ...raises: [], tags: [].}

Treats x and y as unsigned and divides them.

The result is truncated to fit into the result. This implements modulo arithmetic. No overflow errors are possible.

Source   Edit  
proc `/%`(x, y: int8): int8 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `/%`(x, y: int16): int16 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `/%`(x, y: int32): int32 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `/%`(x, y: int64): int64 {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `/=`(x: var float64; y: float64) {.inline, noSideEffect, ...raises: [],
                                        tags: [].}
Divides in place a floating point number. Source   Edit  
proc `/=`[T: float | float32](x: var T; y: T) {.inline, noSideEffect.}
Divides in place a floating point number. Source   Edit  
proc `<`(x, y: bool): bool {.magic: "LtB", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<`(x, y: char): bool {.magic: "LtCh", noSideEffect, ...raises: [], tags: [].}
Compares two chars and returns true if x is lexicographically before y (uppercase letters come before lowercase letters).

Example:

let
  a = 'a'
  b = 'b'
  c = 'Z'
assert a < b
assert not (a < a)
assert not (a < c)
Source   Edit  
proc `<`(x, y: float): bool {.magic: "LtF64", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<`(x, y: float32): bool {.magic: "LtF64", noSideEffect, ...raises: [],
                                tags: [].}
Source   Edit  
proc `<`(x, y: int): bool {.magic: "LtI", noSideEffect, ...raises: [], tags: [].}
Returns true if x is less than y. Source   Edit  
proc `<`(x, y: int8): bool {.magic: "LtI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<`(x, y: int16): bool {.magic: "LtI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<`(x, y: int32): bool {.magic: "LtI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<`(x, y: int64): bool {.magic: "LtI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<`(x, y: pointer): bool {.magic: "LtPtr", noSideEffect, ...raises: [],
                                tags: [].}
Source   Edit  
proc `<`(x, y: string): bool {.magic: "LtStr", noSideEffect, ...raises: [],
                               tags: [].}
Compares two strings and returns true if x is lexicographically before y (uppercase letters come before lowercase letters).

Example:

let
  a = "abc"
  b = "abd"
  c = "ZZZ"
assert a < b
assert not (a < a)
assert not (a < c)
Source   Edit  
proc `<`(x, y: uint): bool {.magic: "LtU", noSideEffect, ...raises: [], tags: [].}
Returns true if x < y. Source   Edit  
proc `<`(x, y: uint8): bool {.magic: "LtU", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<`(x, y: uint16): bool {.magic: "LtU", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<`(x, y: uint32): bool {.magic: "LtU", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<`(x, y: uint64): bool {.magic: "LtU", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<`[Enum: enum](x, y: Enum): bool {.magic: "LtEnum", noSideEffect,
    ...raises: [], tags: [].}
Source   Edit  
proc `<`[T: tuple](x, y: T): bool
Generic lexicographic < operator for tuples that is lifted from the components of x and y. This implementation uses cmp. Source   Edit  
proc `<`[T](x, y: ptr T): bool {.magic: "LtPtr", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `<`[T](x, y: ref T): bool {.magic: "LtPtr", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `<`[T](x, y: set[T]): bool {.magic: "LtSet", noSideEffect, ...raises: [],
                                  tags: [].}

Returns true if x is a strict or proper subset of y.

A strict or proper subset x has all of its members in y but y has more elements than y.

Example:

let
  a = {3, 5}
  b = {1, 3, 5, 7}
  c = {2}
assert a < b
assert not (a < a)
assert not (a < c)
Source   Edit  
proc `<%`(x, y: int): bool {.inline, ...raises: [], tags: [].}
Treats x and y as unsigned and compares them. Returns true if unsigned(x) < unsigned(y). Source   Edit  
proc `<%`(x, y: int8): bool {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `<%`(x, y: int16): bool {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `<%`(x, y: int32): bool {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `<%`(x, y: int64): bool {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `<=`(x, y: bool): bool {.magic: "LeB", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<=`(x, y: char): bool {.magic: "LeCh", noSideEffect, ...raises: [], tags: [].}
Compares two chars and returns true if x is lexicographically before y (uppercase letters come before lowercase letters).

Example:

let
  a = 'a'
  b = 'b'
  c = 'Z'
assert a <= b
assert a <= a
assert not (a <= c)
Source   Edit  
proc `<=`(x, y: float): bool {.magic: "LeF64", noSideEffect, ...raises: [],
                               tags: [].}
Source   Edit  
proc `<=`(x, y: float32): bool {.magic: "LeF64", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `<=`(x, y: int): bool {.magic: "LeI", noSideEffect, ...raises: [], tags: [].}
Returns true if x is less than or equal to y. Source   Edit  
proc `<=`(x, y: int8): bool {.magic: "LeI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<=`(x, y: int16): bool {.magic: "LeI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<=`(x, y: int32): bool {.magic: "LeI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<=`(x, y: int64): bool {.magic: "LeI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<=`(x, y: pointer): bool {.magic: "LePtr", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `<=`(x, y: string): bool {.magic: "LeStr", noSideEffect, ...raises: [],
                                tags: [].}
Compares two strings and returns true if x is lexicographically before y (uppercase letters come before lowercase letters).

Example:

let
  a = "abc"
  b = "abd"
  c = "ZZZ"
assert a <= b
assert a <= a
assert not (a <= c)
Source   Edit  
proc `<=`(x, y: uint): bool {.magic: "LeU", noSideEffect, ...raises: [], tags: [].}
Returns true if x <= y. Source   Edit  
proc `<=`(x, y: uint8): bool {.magic: "LeU", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<=`(x, y: uint16): bool {.magic: "LeU", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<=`(x, y: uint32): bool {.magic: "LeU", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<=`(x, y: uint64): bool {.magic: "LeU", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `<=`[Enum: enum](x, y: Enum): bool {.magic: "LeEnum", noSideEffect,
    ...raises: [], tags: [].}
Source   Edit  
proc `<=`[T: tuple](x, y: T): bool
Generic lexicographic <= operator for tuples that is lifted from the components of x and y. This implementation uses cmp. Source   Edit  
proc `<=`[T](x, y: ref T): bool {.magic: "LePtr", noSideEffect, ...raises: [],
                                  tags: [].}
Source   Edit  
proc `<=`[T](x, y: set[T]): bool {.magic: "LeSet", noSideEffect, ...raises: [],
                                   tags: [].}

Returns true if x is a subset of y.

A subset x has all of its members in y and y doesn't necessarily have more members than x. That is, x can be equal to y.

Example:

let
  a = {3, 5}
  b = {1, 3, 5, 7}
  c = {2}
assert a <= b
assert a <= a
assert not (a <= c)
Source   Edit  
proc `<=%`(x, y: int): bool {.inline, ...raises: [], tags: [].}
Treats x and y as unsigned and compares them. Returns true if unsigned(x) <= unsigned(y). Source   Edit  
proc `<=%`(x, y: int8): bool {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `<=%`(x, y: int16): bool {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `<=%`(x, y: int32): bool {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `<=%`(x, y: int64): bool {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `=`[T](dest: var T; src: T) {.noSideEffect, magic: "Asgn", ...raises: [],
                                   tags: [].}
Source   Edit  
proc `==`(x, y: bool): bool {.magic: "EqB", noSideEffect, ...raises: [], tags: [].}
Checks for equality between two bool variables. Source   Edit  
proc `==`(x, y: char): bool {.magic: "EqCh", noSideEffect, ...raises: [], tags: [].}
Checks for equality between two char variables. Source   Edit  
proc `==`(x, y: cstring): bool {.magic: "EqCString", noSideEffect, inline,
                                 ...raises: [], tags: [].}
Checks for equality between two cstring variables. Source   Edit  
proc `==`(x, y: float): bool {.magic: "EqF64", noSideEffect, ...raises: [],
                               tags: [].}
Source   Edit  
proc `==`(x, y: float32): bool {.magic: "EqF64", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `==`(x, y: int): bool {.magic: "EqI", noSideEffect, ...raises: [], tags: [].}
Compares two integers for equality. Source   Edit  
proc `==`(x, y: int8): bool {.magic: "EqI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `==`(x, y: int16): bool {.magic: "EqI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `==`(x, y: int32): bool {.magic: "EqI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `==`(x, y: int64): bool {.magic: "EqI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `==`(x, y: pointer): bool {.magic: "EqRef", noSideEffect, ...raises: [],
                                 tags: [].}
Checks for equality between two pointer variables.

Example:

var # this is a wildly dangerous example
  a = cast[pointer](0)
  b = cast[pointer](nil)
assert a == b # true due to the special meaning of `nil`/0 as a pointer
Source   Edit  
proc `==`(x, y: string): bool {.magic: "EqStr", noSideEffect, ...raises: [],
                                tags: [].}
Checks for equality between two string variables. Source   Edit  
proc `==`(x, y: uint): bool {.magic: "EqI", noSideEffect, ...raises: [], tags: [].}
Compares two unsigned integers for equality. Source   Edit  
proc `==`(x, y: uint8): bool {.magic: "EqI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `==`(x, y: uint16): bool {.magic: "EqI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `==`(x, y: uint32): bool {.magic: "EqI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `==`(x, y: uint64): bool {.magic: "EqI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `==`(x: string; y: typeof(nil) | typeof(nil)): bool {.
    error: "\'nil\' is now invalid for \'string\'".}
Source   Edit  
proc `==`(x: typeof(nil) | typeof(nil); y: string): bool {.
    error: "\'nil\' is now invalid for \'string\'".}
Source   Edit  
proc `==`[Enum: enum](x, y: Enum): bool {.magic: "EqEnum", noSideEffect,
    ...raises: [], tags: [].}
Checks whether values within the same enum have the same underlying value.

Example:

type
  Enum1 = enum
    field1 = 3, field2
  Enum2 = enum
    place1, place2 = 3
var
  e1 = field1
  e2 = place2.ord.Enum1
assert e1 == e2
assert not compiles(e1 == place2) # raises error
Source   Edit  
proc `==`[I, T](x, y: array[I, T]): bool
Source   Edit  
proc `==`[T: proc](x, y: T): bool {.magic: "EqProc", noSideEffect, ...raises: [],
                                    tags: [].}
Checks that two proc variables refer to the same procedure. Source   Edit  
proc `==`[T: tuple | object](x, y: T): bool
Generic == operator for tuples that is lifted from the components. of x and y. Source   Edit  
proc `==`[T](x, y: openArray[T]): bool
Source   Edit  
proc `==`[T](x, y: ptr T): bool {.magic: "EqRef", noSideEffect, ...raises: [],
                                  tags: [].}
Checks that two ptr variables refer to the same item. Source   Edit  
proc `==`[T](x, y: ref T): bool {.magic: "EqRef", noSideEffect, ...raises: [],
                                  tags: [].}
Checks that two ref variables refer to the same item. Source   Edit  
proc `==`[T](x, y: seq[T]): bool {.noSideEffect.}
Generic equals operator for sequences: relies on a equals operator for the element type T. Source   Edit  
proc `==`[T](x, y: set[T]): bool {.magic: "EqSet", noSideEffect, ...raises: [],
                                   tags: [].}
Checks for equality between two variables of type set.

Example:

assert {1, 2, 2, 3} == {1, 2, 3} # duplication in sets is ignored
Source   Edit  
proc `=copy`[T](dest: var T; src: T) {.noSideEffect, magic: "Asgn", ...raises: [],
                                       tags: [].}
Source   Edit  
proc `=destroy`[T](x: var T) {.inline, magic: "Destroy", ...raises: [], tags: [].}
Generic destructor implementation that can be overridden. Source   Edit  
proc `=sink`[T](x: var T; y: T) {.inline, magic: "Asgn", ...raises: [], tags: [].}
Generic sink implementation that can be overridden. Source   Edit  
proc `=trace`[T](x: var T; env: pointer) {.inline, magic: "Trace", ...raises: [],
    tags: [].}
Generic trace implementation that can be overridden. Source   Edit  
proc `@`[IDX, T](a: sink array[IDX, T]): seq[T] {.magic: "ArrToSeq",
    noSideEffect, ...raises: [], tags: [].}

Turns an array into a sequence.

This most often useful for constructing sequences with the array constructor: @[1, 2, 3] has the type seq[int], while [1, 2, 3] has the type array[0..2, int].

let
  a = [1, 3, 5]
  b = "foo"

echo @a # => @[1, 3, 5]
echo @b # => @['f', 'o', 'o']
Source   Edit  
proc `@`[T](a: openArray[T]): seq[T]

Turns an openArray into a sequence.

This is not as efficient as turning a fixed length array into a sequence as it always copies every element of a.

Source   Edit  
proc `[]`(s: string; i: BackwardsIndex): char {.inline, ...raises: [], tags: [].}
Source   Edit  
proc `[]`(s: var string; i: BackwardsIndex): var char {.inline, ...raises: [],
    tags: [].}
Source   Edit  
proc `[]`[I: Ordinal; T](a: T; i: I): T {.noSideEffect, magic: "ArrGet",
    ...raises: [], tags: [].}
Source   Edit  
proc `[]`[Idx, T; U, V: Ordinal](a: array[Idx, T]; x: HSlice[U, V]): seq[T]
Slice operation for arrays. Returns the inclusive range [a[x.a], a[x.b]]:
var a = [1, 2, 3, 4]
assert a[0..2] == @[1, 2, 3]
Source   Edit  
proc `[]`[Idx, T](a: array[Idx, T]; i: BackwardsIndex): T {.inline.}
Source   Edit  
proc `[]`[Idx, T](a: var array[Idx, T]; i: BackwardsIndex): var T {.inline.}
Source   Edit  
proc `[]`[T, U: Ordinal](s: string; x: HSlice[T, U]): string {.inline.}
Slice operation for strings. Returns the inclusive range [s[x.a], s[x.b]]:
var s = "abcdef"
assert s[1..3] == "bcd"
Source   Edit  
proc `[]`[T; U, V: Ordinal](s: openArray[T]; x: HSlice[U, V]): seq[T]
Slice operation for sequences. Returns the inclusive range [s[x.a], s[x.b]]:
var s = @[1, 2, 3, 4]
assert s[0..2] == @[1, 2, 3]
Source   Edit  
proc `[]`[T](s: openArray[T]; i: BackwardsIndex): T {.inline.}
Source   Edit  
proc `[]`[T](s: var openArray[T]; i: BackwardsIndex): var T {.inline.}
Source   Edit  
proc `[]=`(s: var string; i: BackwardsIndex; x: char) {.inline, ...raises: [],
    tags: [].}
Source   Edit  
proc `[]=`[I: Ordinal; T, S](a: T; i: I; x: sink S) {.noSideEffect,
    magic: "ArrPut", ...raises: [], tags: [].}
Source   Edit  
proc `[]=`[Idx, T; U, V: Ordinal](a: var array[Idx, T]; x: HSlice[U, V];
                                  b: openArray[T])
Slice assignment for arrays.
var a = [10, 20, 30, 40, 50]
a[1..2] = @[99, 88]
assert a == [10, 99, 88, 40, 50]
Source   Edit  
proc `[]=`[Idx, T](a: var array[Idx, T]; i: BackwardsIndex; x: T) {.inline.}
Source   Edit  
proc `[]=`[T, U: Ordinal](s: var string; x: HSlice[T, U]; b: string)

Slice assignment for strings.

If b.len is not exactly the number of elements that are referred to by x, a splice is performed:

Example:

var s = "abcdefgh"
s[1 .. ^2] = "xyz"
assert s == "axyzh"
Source   Edit  
proc `[]=`[T; U, V: Ordinal](s: var seq[T]; x: HSlice[U, V]; b: openArray[T])

Slice assignment for sequences.

If b.len is not exactly the number of elements that are referred to by x, a splice is performed.

Example:

var s = @"abcdefgh"
s[1 .. ^2] = @"xyz"
assert s == @"axyzh"
Source   Edit  
proc `[]=`[T](s: var openArray[T]; i: BackwardsIndex; x: T) {.inline.}
Source   Edit  
func abs(x: int): int {.magic: "AbsI", inline, ...raises: [], tags: [].}
Source   Edit  
func abs(x: int8): int8 {.magic: "AbsI", inline, ...raises: [], tags: [].}
Source   Edit  
func abs(x: int16): int16 {.magic: "AbsI", inline, ...raises: [], tags: [].}
Source   Edit  
func abs(x: int32): int32 {.magic: "AbsI", inline, ...raises: [], tags: [].}
Source   Edit  
func abs(x: int64): int64 {.magic: "AbsI", inline, ...raises: [], tags: [].}

Returns the absolute value of x.

If x is low(x) (that is -MININT for its type), an overflow exception is thrown (if overflow checking is turned on).

Source   Edit  
proc abs[T: float64 | float32](x: T): T {.noSideEffect, inline.}
Source   Edit  
proc add(x: var cstring; y: cstring) {.magic: "AppendStrStr", ...raises: [],
                                       tags: [].}
Appends y to x in place. Only implemented for JS backend.

Example:

when defined(js):
  var tmp: cstring = ""
  tmp.add(cstring("ab"))
  tmp.add(cstring("cd"))
  doAssert tmp == cstring("abcd")
Source   Edit  
proc add(x: var string; y: char) {.magic: "AppendStrCh", noSideEffect,
                                   ...raises: [], tags: [].}
Appends y to x in place.
var tmp = ""
tmp.add('a')
tmp.add('b')
assert(tmp == "ab")
Source   Edit  
proc add(x: var string; y: cstring) {.asmNoStackFrame, ...raises: [], tags: [].}
Appends y to x in place.

Example:

var tmp = ""
tmp.add(cstring("ab"))
tmp.add(cstring("cd"))
doAssert tmp == "abcd"
Source   Edit  
proc add(x: var string; y: string) {.magic: "AppendStrStr", noSideEffect,
                                     ...raises: [], tags: [].}

Concatenates x and y in place.

See also strbasics.add.

Example:

var tmp = ""
tmp.add("ab")
tmp.add("cd")
assert tmp == "abcd"
Source   Edit  
proc add[T](x: var seq[T]; y: openArray[T]) {.noSideEffect.}

Generic proc for adding a container y to a container x.

For containers that have an order, add means append. New generic containers should also call their adding proc add for consistency. Generic code becomes much easier to write if the Nim naming scheme is respected.

See also:

var s: seq[string] = @["test2","test2"]
s.add("test") # s <- @[test2, test2, test]
Source   Edit  
proc add[T](x: var seq[T]; y: sink T) {.magic: "AppendSeqElem", noSideEffect,
                                        ...raises: [], tags: [].}

Generic proc for adding a data item y to a container x.

For containers that have an order, add means append. New generic containers should also call their adding proc add for consistency. Generic code becomes much easier to write if the Nim naming scheme is respected.

Source   Edit  
proc addAndFetch(p: ptr int; val: int): int {.inline, ...raises: [], tags: [].}
Source   Edit  
proc addEscapedChar(s: var string; c: char) {.noSideEffect, inline, ...raises: [],
    tags: [].}
Adds a char to string s and applies the following escaping:
  • replaces any \ by \\
  • replaces any ' by \'
  • replaces any " by \"
  • replaces any \a by \\a
  • replaces any \b by \\b
  • replaces any \t by \\t
  • replaces any \n by \\n
  • replaces any \v by \\v
  • replaces any \f by \\f
  • replaces any \r by \\r
  • replaces any \e by \\e
  • replaces any other character not in the set {\21..\126} by \xHH where HH is its hexadecimal value

The procedure has been designed so that its output is usable for many different common syntaxes.

Warning: This is not correct for producing ANSI C code!
Source   Edit  
proc addQuitProc(quitProc: proc () {.noconv.}) {.importc: "atexit",
    header: "<stdlib.h>", ...deprecated: "use exitprocs.addExitProc", raises: [],
    tags: [].}
Deprecated: use exitprocs.addExitProc

Adds/registers a quit procedure.

Each call to addQuitProc registers another quit procedure. Up to 30 procedures can be registered. They are executed on a last-in, first-out basis (that is, the last function registered is the first to be executed). addQuitProc raises an EOutOfIndex exception if quitProc cannot be registered.

Source   Edit  
proc addQuoted[T](s: var string; x: T)

Appends x to string s in place, applying quoting and escaping if x is a string or char.

See addEscapedChar for the escaping scheme. When x is a string, characters in the range {\128..\255} are never escaped so that multibyte UTF-8 characters are untouched (note that this behavior is different from addEscapedChar).

The Nim standard library uses this function on the elements of collections when producing a string representation of a collection. It is recommended to use this function as well for user-side collections. Users may overload addQuoted for custom (string-like) types if they want to implement a customized element representation.

var tmp = ""
tmp.addQuoted(1)
tmp.add(", ")
tmp.addQuoted("string")
tmp.add(", ")
tmp.addQuoted('c')
assert(tmp == """1, "string", 'c'""")
Source   Edit  
proc `addr`[T](x: T): ptr T {.magic: "Addr", noSideEffect, ...raises: [], tags: [].}
Builtin addr operator for taking the address of a memory location.
Note: This works for let variables or parameters for better interop with C. When you use it to write a wrapper for a C library and take the address of let variables or parameters, you should always check that the original library does never write to data behind the pointer that is returned from this procedure.

Cannot be overloaded.

var
  buf: seq[char] = @['a','b','c']
  p = buf[1].addr
echo p.repr # ref 0x7faa35c40059 --> 'b'
echo p[]    # b
Source   Edit  
proc alignof(x: typedesc): int {.magic: "AlignOf", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc alignof[T](x: T): int {.magic: "AlignOf", noSideEffect, ...raises: [],
                             tags: [].}
Source   Edit  
proc alloc0Impl(size: Natural): pointer {.noconv, ...gcsafe, tags: [], gcsafe,
    locks: 0, ...raises: [].}
Source   Edit  
proc allocCStringArray(a: openArray[string]): cstringArray {....raises: [],
    tags: [].}
Creates a NULL terminated cstringArray from a. The result has to be freed with deallocCStringArray after it's not needed anymore. Source   Edit  
proc allocImpl(size: Natural): pointer {.noconv, ...gcsafe, tags: [], gcsafe,
    locks: 0, ...raises: [].}
Source   Edit  
proc allocShared0Impl(size: Natural): pointer {.noconv, ...gcsafe, gcsafe,
    locks: 0, ...raises: [], tags: [].}
Source   Edit  
proc allocSharedImpl(size: Natural): pointer {.noconv, compilerproc, ...gcsafe,
    gcsafe, locks: 0, ...raises: [], tags: [].}
Source   Edit  
proc `and`(a, b: typedesc): typedesc {.magic: "TypeTrait", noSideEffect,
                                       ...raises: [], tags: [].}
Constructs an and meta class. Source   Edit  
proc `and`(x, y: bool): bool {.magic: "And", noSideEffect, ...raises: [], tags: [].}

Boolean and; returns true if x == y == true (if both arguments are true).

Evaluation is lazy: if x is false, y will not even be evaluated.

Source   Edit  
proc `and`(x, y: int): int {.magic: "BitandI", noSideEffect, ...raises: [],
                             tags: [].}
Computes the bitwise and of numbers x and y.

Example:

assert (0b0011 and 0b0101) == 0b0001
assert (0b0111 and 0b1100) == 0b0100
Source   Edit  
proc `and`(x, y: int8): int8 {.magic: "BitandI", noSideEffect, ...raises: [],
                               tags: [].}
Source   Edit  
proc `and`(x, y: int16): int16 {.magic: "BitandI", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `and`(x, y: int32): int32 {.magic: "BitandI", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `and`(x, y: int64): int64 {.magic: "BitandI", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `and`(x, y: uint): uint {.magic: "BitandI", noSideEffect, ...raises: [],
                               tags: [].}
Computes the bitwise and of numbers x and y. Source   Edit  
proc `and`(x, y: uint8): uint8 {.magic: "BitandI", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `and`(x, y: uint16): uint16 {.magic: "BitandI", noSideEffect, ...raises: [],
                                   tags: [].}
Source   Edit  
proc `and`(x, y: uint32): uint32 {.magic: "BitandI", noSideEffect, ...raises: [],
                                   tags: [].}
Source   Edit  
proc `and`(x, y: uint64): uint64 {.magic: "BitandI", noSideEffect, ...raises: [],
                                   tags: [].}
Source   Edit  
proc ashr(x: int8; y: SomeInteger): int8 {.magic: "AshrI", noSideEffect,
    ...raises: [], tags: [].}
Source   Edit  
proc ashr(x: int16; y: SomeInteger): int16 {.magic: "AshrI", noSideEffect,
    ...raises: [], tags: [].}
Source   Edit  
proc ashr(x: int32; y: SomeInteger): int32 {.magic: "AshrI", noSideEffect,
    ...raises: [], tags: [].}
Source   Edit  
proc ashr(x: int64; y: SomeInteger): int64 {.magic: "AshrI", noSideEffect,
    ...raises: [], tags: [].}
Source   Edit  
proc ashr(x: int; y: SomeInteger): int {.magic: "AshrI", noSideEffect,
    ...raises: [], tags: [].}

Shifts right by pushing copies of the leftmost bit in from the left, and let the rightmost bits fall off.

Note that ashr is not an operator so use the normal function call syntax for it.

See also:

Example:

assert ashr(0b0001_0000'i8, 2) == 0b0000_0100'i8
assert ashr(0b1000_0000'i8, 8) == 0b1111_1111'i8
assert ashr(0b1000_0000'i8, 1) == 0b1100_0000'i8
Source   Edit  
proc astToStr[T](x: T): string {.magic: "AstToStr", noSideEffect, ...raises: [],
                                 tags: [].}
Converts the AST of x into a string representation. This is very useful for debugging. Source   Edit  
proc atomicDec(memLoc: var int; x: int = 1): int {.inline, discardable, ...gcsafe,
    locks: 0, ...raises: [], tags: [].}
Atomic decrement of memLoc. Returns the value after the operation. Source   Edit  
proc atomicInc(memLoc: var int; x: int = 1): int {.inline, discardable, ...gcsafe,
    locks: 0, ...raises: [], tags: [].}
Atomic increment of memLoc. Returns the value after the operation. Source   Edit  
func card[T](x: set[T]): int {.magic: "Card", ...raises: [], tags: [].}
Returns the cardinality of the set x, i.e. the number of elements in the set.

Example:

var a = {1, 3, 5, 7}
assert card(a) == 4
var b = {1, 3, 5, 7, 5}
assert card(b) == 4 # repeated 5 doesn't count
Source   Edit  
proc cas[T: bool | int | ptr](p: ptr T; oldValue, newValue: T): bool {.
    importc: "__sync_bool_compare_and_swap", nodecl, ...raises: [], tags: [].}
Source   Edit  
func chr(u: range[0 .. 255]): char {.magic: "Chr", ...raises: [], tags: [].}
Converts u to a char, same as char(u).

Example:

doAssert chr(65) == 'A'
doAssert chr(255) == '\255'
doAssert chr(255) == char(255)
doAssert not compiles chr(256)
doAssert not compiles char(256)
var x = 256
doAssertRaises(RangeDefect): discard chr(x)
doAssertRaises(RangeDefect): discard char(x)
Source   Edit  
proc clamp[T](x, a, b: T): T
Limits the value x within the interval [a, b]. This proc is equivalent to but faster than max(a, min(b, x)).
Warning: a <= b is assumed and will not be checked (currently).

See also: math.clamp for a version that takes a Slice[T] instead.

Example:

assert (1.4).clamp(0.0, 1.0) == 1.0
assert (0.5).clamp(0.0, 1.0) == 0.5
assert 4.clamp(1, 3) == max(1, min(3, 4))
Source   Edit  
proc cmp(x, y: string): int {.noSideEffect, ...raises: [], tags: [].}

Compare proc for strings. More efficient than the generic version.

Note: The precise result values depend on the used C runtime library and can differ between operating systems!

Source   Edit  
proc cmp[T](x, y: T): int

Generic compare proc.

Returns:

  • a value less than zero, if x < y
  • a value greater than zero, if x > y
  • zero, if x == y

This is useful for writing generic algorithms without performance loss. This generic implementation uses the == and < operators.

import std/algorithm
echo sorted(@[4, 2, 6, 5, 8, 7], cmp[int])
Source   Edit  
proc cmpMem(a, b: pointer; size: Natural): int {.inline, noSideEffect, ...tags: [],
    locks: 0, ...raises: [].}

Compares the memory blocks a and b. size bytes will be compared.

Returns:

  • a value less than zero, if a < b
  • a value greater than zero, if a > b
  • zero, if a == b

Like any procedure dealing with raw memory this is unsafe.

Source   Edit  
proc compileOption(option, arg: string): bool {.magic: "CompileOptionArg",
    noSideEffect, ...raises: [], tags: [].}

Can be used to determine an enum compile-time option.

See also:

Example:

when compileOption("opt", "size") and compileOption("gc", "boehm"):
  discard "compiled with optimization for size and uses Boehm's GC"
Source   Edit  
proc compileOption(option: string): bool {.magic: "CompileOption", noSideEffect,
    ...raises: [], tags: [].}

Can be used to determine an on|off compile-time option.

See also:

Example: cmd: --floatChecks:off

static: doAssert not compileOption("floatchecks")
{.push floatChecks: on.}
static: doAssert compileOption("floatchecks")
# floating point NaN and Inf checks enabled in this scope
{.pop.}
Source   Edit  
proc compiles(x: untyped): bool {.magic: "Compiles", noSideEffect, compileTime,
                                  ...raises: [], tags: [].}
Special compile-time procedure that checks whether x can be compiled without any semantic error. This can be used to check whether a type supports some operation:
when compiles(3 + 4):
  echo "'+' for integers is available"
Source   Edit  
proc contains[T](a: openArray[T]; item: T): bool {.inline.}

Returns true if item is in a or false if not found. This is a shortcut for find(a, item) >= 0.

This allows the in operator: a.contains(item) is the same as item in a.

var a = @[1, 3, 5]
assert a.contains(5)
assert 3 in a
assert 99 notin a
Source   Edit  
func contains[T](x: set[T]; y: T): bool {.magic: "InSet", ...raises: [], tags: [].}

One should overload this proc if one wants to overload the in operator.

The parameters are in reverse order! a in b is a template for contains(b, a). This is because the unification algorithm that Nim uses for overload resolution works from left to right. But for the in operator that would be the wrong direction for this piece of code:

Example:

var s: set[range['a'..'z']] = {'a'..'c'}
assert s.contains('c')
assert 'b' in s
assert 'd' notin s
assert set['a'..'z'] is set[range['a'..'z']]
If in had been declared as [T](elem: T, s: set[T]) then T would have been bound to char. But s is not compatible to type set[char]! The solution is to bind T to range['a'..'z']. This is achieved by reversing the parameters for contains; in then passes its arguments in reverse order. Source   Edit  
proc contains[U, V, W](s: HSlice[U, V]; value: W): bool {.noSideEffect, inline.}
Checks if value is within the range of s; returns true if value >= s.a and value <= s.b
assert((1..3).contains(1) == true)
assert((1..3).contains(2) == true)
assert((1..3).contains(4) == false)
Source   Edit  
proc copyMem(dest, source: pointer; size: Natural) {.inline, ...gcsafe, locks: 0,
    ...tags: [], locks: 0, ...raises: [].}
Copies the contents from the memory at source to the memory at dest. Exactly size bytes will be copied. The memory regions may not overlap. Like any procedure dealing with raw memory this is unsafe. Source   Edit  
proc cpuRelax() {.inline, ...raises: [], tags: [].}
Source   Edit  
proc create(T: typedesc; size = 1.Positive): ptr T:type {.inline, ...gcsafe,
    locks: 0, ...raises: [].}

Allocates a new memory block with at least T.sizeof * size bytes.

The block has to be freed with resize(block, 0) or dealloc(block). The block is initialized with all bytes containing zero, so it is somewhat safer than createU.

The allocated memory belongs to its allocating thread! Use createShared to allocate from a shared heap.

Source   Edit  
proc createShared(T: typedesc; size = 1.Positive): ptr T:type {.inline.}

Allocates a new memory block on the shared heap with at least T.sizeof * size bytes.

The block has to be freed with resizeShared(block, 0) or freeShared(block).

The block is initialized with all bytes containing zero, so it is somewhat safer than createSharedU.

Source   Edit  
proc createSharedU(T: typedesc; size = 1.Positive): ptr T:type {.inline,
    ...tags: [], gcsafe, locks: 0, ...raises: [].}

Allocates a new memory block on the shared heap with at least T.sizeof * size bytes.

The block has to be freed with resizeShared(block, 0) or freeShared(block).

The block is not initialized, so reading from it before writing to it is undefined behaviour!

See also:

Source   Edit  
proc createU(T: typedesc; size = 1.Positive): ptr T:type {.inline, ...gcsafe,
    locks: 0, ...raises: [].}

Allocates a new memory block with at least T.sizeof * size bytes.

The block has to be freed with resize(block, 0) or dealloc(block). The block is not initialized, so reading from it before writing to it is undefined behaviour!

The allocated memory belongs to its allocating thread! Use createSharedU to allocate from a shared heap.

See also:

Source   Edit  
proc cstringArrayToSeq(a: cstringArray): seq[string] {....raises: [], tags: [].}
Converts a cstringArray to a seq[string]. a is supposed to be terminated by nil. Source   Edit  
proc cstringArrayToSeq(a: cstringArray; len: Natural): seq[string] {....raises: [],
    tags: [].}
Converts a cstringArray to a seq[string]. a is supposed to be of length len. Source   Edit  
proc dealloc(p: pointer) {.noconv, compilerproc, ...gcsafe, gcsafe, locks: 0,
                           ...raises: [], tags: [].}

Frees the memory allocated with alloc, alloc0, realloc, create or createU.

This procedure is dangerous! If one forgets to free the memory a leak occurs; if one tries to access freed memory (or just freeing it twice!) a core dump may happen or other memory may be corrupted.

The freed memory must belong to its allocating thread! Use deallocShared to deallocate from a shared heap.

Source   Edit  
proc deallocCStringArray(a: cstringArray) {....raises: [], tags: [].}
Frees a NULL terminated cstringArray. Source   Edit  
proc deallocHeap(runFinalizers = true; allowGcAfterwards = true) {....raises: [],
    tags: [RootEffect].}
Frees the thread local heap. Runs every finalizer if runFinalizers is true. If allowGcAfterwards is true, a minimal amount of allocation happens to ensure the GC can continue to work after the call to deallocHeap. Source   Edit  
proc deallocImpl(p: pointer) {.noconv, ...gcsafe, tags: [], gcsafe, locks: 0,
                               ...raises: [].}
Source   Edit  
proc deallocShared(p: pointer) {.noconv, compilerproc, ...gcsafe, gcsafe, locks: 0,
                                 ...raises: [], tags: [].}

Frees the memory allocated with allocShared, allocShared0 or reallocShared.

This procedure is dangerous! If one forgets to free the memory a leak occurs; if one tries to access freed memory (or just freeing it twice!) a core dump may happen or other memory may be corrupted.

Source   Edit  
proc deallocSharedImpl(p: pointer) {.noconv, ...gcsafe, gcsafe, locks: 0,
                                     ...raises: [], tags: [].}
Source   Edit  
proc debugEcho(x: varargs[typed, `$`]) {.magic: "Echo", noSideEffect, ...tags: [],
    raises: [].}
Same as echo, but as a special semantic rule, debugEcho pretends to be free of side effects, so that it can be used for debugging routines marked as noSideEffect. Source   Edit  
proc dec[T: Ordinal](x: var T; y = 1) {.magic: "Dec", noSideEffect, ...raises: [],
                                        tags: [].}

Decrements the ordinal x by y.

If such a value does not exist, OverflowDefect is raised or a compile time error occurs. This is a short notation for: x = pred(x, y).

Example:

var i = 2
dec(i)
assert i == 1
dec(i, 3)
assert i == -2
Source   Edit  
proc declared(x: untyped): bool {.magic: "Declared", noSideEffect, compileTime,
                                  ...raises: [], tags: [].}

Special compile-time procedure that checks whether x is declared. x has to be an identifier or a qualified identifier.

See also:

This can be used to check whether a library provides a certain feature or not:

when not declared(strutils.toUpper):
  # provide our own toUpper proc here, because strutils is
  # missing it.
Source   Edit  
proc declaredInScope(x: untyped): bool {.magic: "DeclaredInScope", noSideEffect,
    compileTime, ...raises: [], tags: [].}
Special compile-time procedure that checks whether x is declared in the current scope. x has to be an identifier. Source   Edit  
proc deepCopy[T](x: var T; y: T) {.noSideEffect, magic: "DeepCopy", ...raises: [],
                                   tags: [].}

Performs a deep copy of y and copies it into x.

This is also used by the code generator for the implementation of spawn.

For --gc:arc or --gc:orc deepcopy support has to be enabled via --deepcopy:on.

Source   Edit  
proc deepCopy[T](y: T): T
Convenience wrapper around deepCopy overload. Source   Edit  
proc default[T](_: typedesc[T]): T {.magic: "Default", noSideEffect, ...raises: [],
                                     tags: [].}
returns the default value of the type T.

Example:

assert (int, float).default == (0, 0.0)
# note: `var a = default(T)` is usually the same as `var a: T` and (currently) generates
# a value whose binary representation is all 0, regardless of whether this
# would violate type constraints such as `range`, `not nil`, etc. This
# property is required to implement certain algorithms efficiently which
# may require intermediate invalid states.
type Foo = object
  a: range[2..6]
var a1: range[2..6] # currently, this compiles
# var a2: Foo # currently, this errors: Error: The Foo type doesn't have a default value.
# var a3 = Foo() # ditto
var a3 = Foo.default # this works, but generates a `UnsafeDefault` warning.
Source   Edit  
proc defined(x: untyped): bool {.magic: "Defined", noSideEffect, compileTime,
                                 ...raises: [], tags: [].}

Special compile-time procedure that checks whether x is defined.

See also:

x is an external symbol introduced through the compiler's -d:x switch to enable build time conditionals:

when not defined(release):
  # Do here programmer friendly expensive sanity checks.
# Put here the normal code
Source   Edit  
proc del[T](x: var seq[T]; i: Natural) {.noSideEffect.}

Deletes the item at index i by putting x[high(x)] into position i.

This is an O(1) operation.

See also:

  • delete for preserving the order

Example:

var a = @[10, 11, 12, 13, 14]
a.del(2)
assert a == @[10, 11, 14, 13]
Source   Edit  
proc delete[T](x: var seq[T]; i: Natural) {.noSideEffect.}

Deletes the item at index i by moving all x[i+1..^1] items by one position.

This is an O(n) operation.

Note: With -d:nimStrictDelete, an index error is produced when the index passed to it was out of bounds. -d:nimStrictDelete will become the default in upcoming versions.

See also:

  • del for O(1) operation

Example:

var s = @[1, 2, 3, 4, 5]
s.delete(2)
doAssert s == @[1, 2, 4, 5]
Source   Edit  
proc dispose(x: ForeignCell) {....raises: [], tags: [].}
Source   Edit  
proc `div`(x, y: int): int {.magic: "DivI", noSideEffect, ...raises: [], tags: [].}

Computes the integer division.

This is roughly the same as math.trunc(x/y).int.

Example:

assert (1 div 2) == 0
assert (2 div 2) == 1
assert (3 div 2) == 1
assert (7 div 3) == 2
assert (-7 div 3) == -2
assert (7 div -3) == -2
assert (-7 div -3) == 2
Source   Edit  
proc `div`(x, y: int8): int8 {.magic: "DivI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `div`(x, y: int16): int16 {.magic: "DivI", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `div`(x, y: int32): int32 {.magic: "DivI", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `div`(x, y: int64): int64 {.magic: "DivI", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `div`(x, y: uint): uint {.magic: "DivU", noSideEffect, ...raises: [], tags: [].}
Computes the integer division for unsigned integers. This is roughly the same as trunc(x/y). Source   Edit  
proc `div`(x, y: uint8): uint8 {.magic: "DivU", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `div`(x, y: uint16): uint16 {.magic: "DivU", noSideEffect, ...raises: [],
                                   tags: [].}
Source   Edit  
proc `div`(x, y: uint32): uint32 {.magic: "DivU", noSideEffect, ...raises: [],
                                   tags: [].}
Source   Edit  
proc `div`(x, y: uint64): uint64 {.magic: "DivU", noSideEffect, ...raises: [],
                                   tags: [].}
Source   Edit  
proc echo(x: varargs[typed, `$`]) {.magic: "Echo", ...gcsafe, locks: 0, sideEffect,
                                    ...raises: [], tags: [].}

Writes and flushes the parameters to the standard output.

Special built-in that takes a variable number of arguments. Each argument is converted to a string via $, so it works for user-defined types that have an overloaded $ operator. It is roughly equivalent to writeLine(stdout, x); flushFile(stdout), but available for the JavaScript target too.

Unlike other IO operations this is guaranteed to be thread-safe as echo is very often used for debugging convenience. If you want to use echo inside a proc without side effects you can use debugEcho instead.

Source   Edit  
proc equalMem(a, b: pointer; size: Natural): bool {.inline, noSideEffect,
    ...tags: [], locks: 0, ...raises: [].}

Compares the memory blocks a and b. size bytes will be compared.

If the blocks are equal, true is returned, false otherwise. Like any procedure dealing with raw memory this is unsafe.

Source   Edit  
func excl[T](x: var set[T]; y: T) {.magic: "Excl", ...raises: [], tags: [].}

Excludes element y from the set x.

This is the same as x = x - {y}, but it might be more efficient.

Example:

var b = {2, 3, 5, 6, 12, 545}
b.excl(5)
assert b == {2, 3, 6, 12, 545}
Source   Edit  
proc find[T, S](a: T; item: S): int {.inline.}
Returns the first index of item in a or -1 if not found. This requires appropriate items and == operations to work. Source   Edit  
proc finished[T: proc](x: T): bool {.noSideEffect, inline, magic: "Finished",
                                     ...raises: [], tags: [].}
It can be used to determine if a first class iterator has finished. Source   Edit  
proc freeShared[T](p: ptr T) {.inline, ...gcsafe, locks: 0, ...raises: [].}

Frees the memory allocated with createShared, createSharedU or resizeShared.

This procedure is dangerous! If one forgets to free the memory a leak occurs; if one tries to access freed memory (or just freeing it twice!) a core dump may happen or other memory may be corrupted.

Source   Edit  
proc GC_collectZct() {....raises: [], tags: [RootEffect].}
Collect the ZCT (zero count table). Unstable, experimental API for testing purposes. DO NOT USE! Source   Edit  
proc GC_disable() {....gcsafe, inline, ...gcsafe, locks: 0, ...raises: [], tags: [].}

Disables the GC. If called n times, n calls to GC_enable are needed to reactivate the GC.

Note that in most circumstances one should only disable the mark and sweep phase with GC_disableMarkAndSweep.

Source   Edit  
proc GC_disableMarkAndSweep() {....gcsafe, gcsafe, locks: 0, ...raises: [], tags: [].}
The current implementation uses a reference counting garbage collector with a seldomly run mark and sweep phase to free cycles. The mark and sweep phase may take a long time and is not needed if the application does not create cycles. Thus the mark and sweep phase can be deactivated and activated separately from the rest of the GC. Source   Edit  
proc GC_enable() {....gcsafe, inline, ...gcsafe, locks: 0, ...raises: [], tags: [].}
Enables the GC again. Source   Edit  
proc GC_enableMarkAndSweep() {....gcsafe, gcsafe, locks: 0, ...raises: [], tags: [].}
Source   Edit  
proc GC_fullCollect() {....gcsafe, gcsafe, locks: 0, ...raises: [], tags: [RootEffect].}
Forces a full garbage collection pass. Ordinary code does not need to call this (and should not). Source   Edit  
proc GC_getStatistics(): string {....gcsafe, gcsafe, locks: 0, ...raises: [], tags: [].}
Returns an informative string about the GC's activity. This may be useful for tweaking. Source   Edit  
proc GC_ref(x: string) {.magic: "GCref", ...gcsafe, locks: 0, ...raises: [], tags: [].}
Marks the object x as referenced, so that it will not be freed until it is unmarked via GC_unref. If called n-times for the same object x, n calls to GC_unref are needed to unmark x. Source   Edit  
proc GC_ref[T](x: ref T) {.magic: "GCref", ...gcsafe, locks: 0, ...raises: [],
                           tags: [].}
Source   Edit  
proc GC_ref[T](x: seq[T]) {.magic: "GCref", ...gcsafe, locks: 0, ...raises: [],
                            tags: [].}
Source   Edit  
proc GC_unref(x: string) {.magic: "GCunref", ...gcsafe, locks: 0, ...raises: [],
                           tags: [].}
See the documentation of GC_ref. Source   Edit  
proc GC_unref[T](x: ref T) {.magic: "GCunref", ...gcsafe, locks: 0, ...raises: [],
                             tags: [].}
Source   Edit  
proc GC_unref[T](x: seq[T]) {.magic: "GCunref", ...gcsafe, locks: 0, ...raises: [],
                              tags: [].}
Source   Edit  
proc gcInvariant() {....raises: [], tags: [].}
Source   Edit  
proc getAllocStats(): AllocStats {....raises: [], tags: [].}
Source   Edit  
proc getCurrentException(): ref Exception {.compilerproc, inline, ...gcsafe,
    locks: 0, ...raises: [], tags: [].}
Retrieves the current exception; if there is none, nil is returned. Source   Edit  
proc getCurrentExceptionMsg(): string {.inline, ...gcsafe, locks: 0, ...raises: [],
                                        tags: [].}
Retrieves the error message that was attached to the current exception; if there is none, "" is returned. Source   Edit  
proc getFrame(): PFrame {.compilerproc, inline, ...raises: [], tags: [].}
Source   Edit  
proc getFrameState(): FrameState {.compilerproc, inline, ...raises: [], tags: [].}
Source   Edit  
proc getFreeMem(): int {....gcsafe, raises: [], tags: [].}
Returns the number of bytes that are owned by the process, but do not hold any meaningful data. Source   Edit  
proc getGcFrame(): GcFrame {.compilerproc, inline, ...raises: [], tags: [].}
Source   Edit  
proc getMaxMem(): int {....raises: [], tags: [].}
Source   Edit  
proc getOccupiedMem(): int {....gcsafe, raises: [], tags: [].}
Returns the number of bytes that are owned by the process and hold data. Source   Edit  
proc getStackTrace(): string {....gcsafe, raises: [], tags: [].}
Gets the current stack trace. This only works for debug builds. Source   Edit  
proc getStackTrace(e: ref Exception): string {....gcsafe, raises: [], tags: [].}
Gets the stack trace associated with e, which is the stack that lead to the raise statement. This only works for debug builds. Source   Edit  
proc getStackTraceEntries(): seq[StackTraceEntry] {....raises: [], tags: [].}
Returns the stack trace entries for the current stack trace. This is not yet available for the JS backend. Source   Edit  
proc getStackTraceEntries(e: ref Exception): lent seq[StackTraceEntry] {.
    ...raises: [], tags: [].}
Source   Edit  
proc getTotalMem(): int {....gcsafe, raises: [], tags: [].}
Returns the number of bytes that are owned by the process. Source   Edit  
proc getTypeInfo[T](x: T): pointer {.magic: "GetTypeInfo", ...gcsafe, locks: 0,
                                     ...raises: [], tags: [].}

Get type information for x.

Ordinary code should not use this, but the typeinfo module instead.

Source   Edit  
proc gorge(command: string; input = ""; cache = ""): string {.
    magic: "StaticExec", ...raises: [], tags: [].}
This is an alias for staticExec. Source   Edit  
proc gorgeEx(command: string; input = ""; cache = ""): tuple[output: string,
    exitCode: int] {....raises: [], tags: [].}
Similar to gorge but also returns the precious exit code. Source   Edit  
proc high(T: typedesc[SomeFloat]): T:type
Source   Edit  
proc high(x: cstring): int {.magic: "High", noSideEffect, ...raises: [], tags: [].}

Returns the highest possible index of a compatible string x. This is sometimes an O(n) operation.

See also:

Source   Edit  
proc high(x: string): int {.magic: "High", noSideEffect, ...raises: [], tags: [].}

Returns the highest possible index of a string x.

See also:

var str = "Hello world!"
high(str) # => 11
Source   Edit  
proc high[I, T](x: array[I, T]): I {.magic: "High", noSideEffect, ...raises: [],
                                     tags: [].}

Returns the highest possible index of an array x.

For empty arrays, the return type is int.

See also:

var arr = [1, 2, 3, 4, 5, 6, 7]
high(arr) # => 6
for i in low(arr)..high(arr):
  echo arr[i]
Source   Edit  
proc high[I, T](x: typedesc[array[I, T]]): I {.magic: "High", noSideEffect,
    ...raises: [], tags: [].}

Returns the highest possible index of an array type.

For empty arrays, the return type is int.

See also:

high(array[7, int]) # => 6
Source   Edit  
proc high[T: Ordinal | enum | range](x: T): T {.magic: "High", noSideEffect, ...deprecated: "Deprecated since v1.4; there should not be `high(value)`. Use `high(type)`.",
    raises: [], tags: [].}
Deprecated: Deprecated since v1.4; there should not be `high(value)`. Use `high(type)`.

Returns the highest possible value of an ordinal value x.

As a special semantic rule, x may also be a type identifier.

This proc is deprecated, use this one instead:

high(2) # => 9223372036854775807
Source   Edit  
proc high[T: Ordinal | enum | range](x: typedesc[T]): T {.magic: "High",
    noSideEffect, ...raises: [], tags: [].}

Returns the highest possible value of an ordinal or enum type.

high(int) is Nim's way of writing INT_MAX or MAX_INT.

See also:

high(int) # => 9223372036854775807
Source   Edit  
proc high[T](x: openArray[T]): int {.magic: "High", noSideEffect, ...raises: [],
                                     tags: [].}

Returns the highest possible index of a sequence x.

See also:

var s = @[1, 2, 3, 4, 5, 6, 7]
high(s) # => 6
for i in low(s)..high(s):
  echo s[i]
Source   Edit  
proc inc[T: Ordinal](x: var T; y = 1) {.magic: "Inc", noSideEffect, ...raises: [],
                                        tags: [].}

Increments the ordinal x by y.

If such a value does not exist, OverflowDefect is raised or a compile time error occurs. This is a short notation for: x = succ(x, y).

Example:

var i = 2
inc(i)
assert i == 3
inc(i, 3)
assert i == 6
Source   Edit  
func incl[T](x: var set[T]; y: T) {.magic: "Incl", ...raises: [], tags: [].}

Includes element y in the set x.

This is the same as x = x + {y}, but it might be more efficient.

Example:

var a = {1, 3, 5}
a.incl(2)
assert a == {1, 2, 3, 5}
a.incl(4)
assert a == {1, 2, 3, 4, 5}
Source   Edit  
proc insert(x: var string; item: string; i = 0.Natural) {.noSideEffect,
    ...raises: [], tags: [].}
Inserts item into x at position i.
var a = "abc"
a.insert("zz", 0) # a <- "zzabc"
Source   Edit  
proc insert[T](x: var seq[T]; item: sink T; i = 0.Natural) {.noSideEffect.}
Inserts item into x at position i.
var i = @[1, 3, 5]
i.insert(99, 0) # i <- @[99, 1, 3, 5]
Source   Edit  
proc instantiationInfo(index = -1; fullPaths = false): tuple[filename: string,
    line: int, column: int] {.magic: "InstantiationInfo", noSideEffect,
                              ...raises: [], tags: [].}

Provides access to the compiler's instantiation stack line information of a template.

While similar to the caller info of other languages, it is determined at compile time.

This proc is mostly useful for meta programming (eg. assert template) to retrieve information about the current filename and line number. Example:

import std/strutils

template testException(exception, code: untyped): typed =
  try:
    let pos = instantiationInfo()
    discard(code)
    echo "Test failure at $1:$2 with '$3'" % [pos.filename,
      $pos.line, astToStr(code)]
    assert false, "A test expecting failure succeeded?"
  except exception:
    discard

proc tester(pos: int): int =
  let
    a = @[1, 2, 3]
  result = a[pos]

when isMainModule:
  testException(IndexDefect, tester(30))
  testException(IndexDefect, tester(1))
  # --> Test failure at example.nim:20 with 'tester(1)'
Source   Edit  
proc internalNew[T](a: var ref T) {.magic: "New", noSideEffect, ...raises: [],
                                    tags: [].}
Leaked implementation detail. Do not use. Source   Edit  
proc `is`[T, S](x: T; y: S): bool {.magic: "Is", noSideEffect, ...raises: [],
                                    tags: [].}

Checks if T is of the same type as S.

For a negated version, use isnot.

assert 42 is int
assert @[1, 2] is seq

proc test[T](a: T): int =
  when (T is int):
    return a
  else:
    return 0

assert(test[int](3) == 3)
assert(test[string]("xyz") == 0)
Source   Edit  
proc isNil(x: cstring): bool {.noSideEffect, magic: "IsNil", ...raises: [],
                               tags: [].}
Source   Edit  
proc isNil(x: pointer): bool {.noSideEffect, magic: "IsNil", ...raises: [],
                               tags: [].}
Source   Edit  
proc isNil(x: string): bool {.noSideEffect, magic: "IsNil", error, ...raises: [],
                              tags: [].}
See also: Source   Edit  
proc isNil[T: proc](x: T): bool {.noSideEffect, magic: "IsNil", ...raises: [],
                                  tags: [].}
Fast check whether x is nil. This is sometimes more efficient than == nil. Source   Edit  
proc isNil[T](x: ptr T): bool {.noSideEffect, magic: "IsNil", ...raises: [],
                                tags: [].}
Source   Edit  
proc isNil[T](x: ref T): bool {.noSideEffect, magic: "IsNil", ...raises: [],
                                tags: [].}
Source   Edit  
proc isNil[T](x: seq[T]): bool {.noSideEffect, magic: "IsNil", error,
                                 ...raises: [], tags: [].}

Seqs are no longer nil by default, but set and empty. Check for zero length instead.

See also:

Source   Edit  
proc isNotForeign(x: ForeignCell): bool {....raises: [], tags: [].}
returns true if 'x' belongs to the calling thread. No deep copy has to be performed then. Source   Edit  
proc iterToProc(iter: typed; envType: typedesc; procName: untyped) {.
    magic: "Plugin", compileTime, ...raises: [], tags: [].}
Source   Edit  
func len(x: (type array) | array): int {.magic: "LengthArray", ...raises: [],
    tags: [].}
Returns the length of an array or an array type. This is roughly the same as high(T)-low(T)+1.

Example:

var a = [1, 1, 1]
assert a.len == 3
assert array[0, float].len == 0
static: assert array[-2..2, float].len == 5
Source   Edit  
proc len(x: cstring): int {.magic: "LengthStr", noSideEffect, ...raises: [],
                            tags: [].}

Returns the length of a compatible string. This is an O(n) operation except in js at runtime.

Note: On the JS backend this currently counts UTF-16 code points instead of bytes at runtime (not at compile time). For now, if you need the byte length of the UTF-8 encoding, convert to string with $ first then call len.

Example:

doAssert len(cstring"abc") == 3
doAssert len(cstring r"ab\0c") == 5 # \0 is escaped
doAssert len(cstring"ab\0c") == 5 # ditto
var a: cstring = "ab\0c"
when defined(js): doAssert a.len == 4 # len ignores \0 for js
else: doAssert a.len == 2 # \0 is a null terminator
static:
  var a2: cstring = "ab\0c"
  doAssert a2.len == 2 # \0 is a null terminator, even in js vm
Source   Edit  
func len(x: string): int {.magic: "LengthStr", ...raises: [], tags: [].}
Returns the length of a string.

Example:

assert "abc".len == 3
assert "".len == 0
assert string.default.len == 0
Source   Edit  
func len[T](x: seq[T]): int {.magic: "LengthSeq", ...raises: [], tags: [].}
Returns the length of x.

Example:

assert @[0, 1].len == 2
assert seq[int].default.len == 0
assert newSeq[int](3).len == 3
let s = newSeqOfCap[int](3)
assert s.len == 0
Source   Edit  
func len[T](x: set[T]): int {.magic: "Card", ...raises: [], tags: [].}
An alias for card(x). Source   Edit  
func len[TOpenArray: openArray | varargs](x: TOpenArray): int {.
    magic: "LengthOpenArray", ...raises: [], tags: [].}
Returns the length of an openArray.

Example:

proc bar[T](a: openArray[T]): int = len(a)
assert bar([1,2]) == 2
assert [1,2].len == 2
Source   Edit  
proc len[U: Ordinal; V: Ordinal](x: HSlice[U, V]): int {.noSideEffect, inline.}
Length of ordinal slice. When x.b < x.a returns zero length.
assert((0..5).len == 6)
assert((5..2).len == 0)
Source   Edit  
proc locals(): RootObj {.magic: "Plugin", noSideEffect, ...raises: [], tags: [].}

Generates a tuple constructor expression listing all the local variables in the current scope.

This is quite fast as it does not rely on any debug or runtime information. Note that in contrast to what the official signature says, the return type is not RootObj but a tuple of a structure that depends on the current scope. Example:

proc testLocals() =
  var
    a = "something"
    b = 4
    c = locals()
    d = "super!"
  
  b = 1
  for name, value in fieldPairs(c):
    echo "name ", name, " with value ", value
  echo "B is ", b
# -> name a with value something
# -> name b with value 4
# -> B is 1
Source   Edit  
proc low(T: typedesc[SomeFloat]): T:type
Source   Edit  
proc low(x: cstring): int {.magic: "Low", noSideEffect, ...raises: [], tags: [].}

Returns the lowest possible index of a compatible string x.

See also:

Source   Edit  
proc low(x: string): int {.magic: "Low", noSideEffect, ...raises: [], tags: [].}

Returns the lowest possible index of a string x.

See also:

var str = "Hello world!"
low(str) # => 0
Source   Edit  
proc low[I, T](x: array[I, T]): I {.magic: "Low", noSideEffect, ...raises: [],
                                    tags: [].}

Returns the lowest possible index of an array x.

For empty arrays, the return type is int.

See also:

var arr = [1, 2, 3, 4, 5, 6, 7]
low(arr) # => 0
for i in low(arr)..high(arr):
  echo arr[i]
Source   Edit  
proc low[I, T](x: typedesc[array[I, T]]): I {.magic: "Low", noSideEffect,
    ...raises: [], tags: [].}

Returns the lowest possible index of an array type.

For empty arrays, the return type is int.

See also:

low(array[7, int]) # => 0
Source   Edit  
proc low[T: Ordinal | enum | range](x: T): T {.magic: "Low", noSideEffect, ...deprecated: "Deprecated since v1.4; there should not be `low(value)`. Use `low(type)`.",
    raises: [], tags: [].}
Deprecated: Deprecated since v1.4; there should not be `low(value)`. Use `low(type)`.

Returns the lowest possible value of an ordinal value x. As a special semantic rule, x may also be a type identifier.

This proc is deprecated, use this one instead:

low(2) # => -9223372036854775808
Source   Edit  
proc low[T: Ordinal | enum | range](x: typedesc[T]): T {.magic: "Low",
    noSideEffect, ...raises: [], tags: [].}

Returns the lowest possible value of an ordinal or enum type.

low(int) is Nim's way of writing INT_MIN or MIN_INT.

See also:

low(int) # => -9223372036854775808
Source   Edit  
proc low[T](x: openArray[T]): int {.magic: "Low", noSideEffect, ...raises: [],
                                    tags: [].}

Returns the lowest possible index of a sequence x.

See also:

var s = @[1, 2, 3, 4, 5, 6, 7]
low(s) # => 0
for i in low(s)..high(s):
  echo s[i]
Source   Edit  
proc max(x, y: float32): float32 {.noSideEffect, inline, ...raises: [], tags: [].}
Source   Edit  
proc max(x, y: float64): float64 {.noSideEffect, inline, ...raises: [], tags: [].}
Source   Edit  
proc max(x, y: int): int {.magic: "MaxI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc max(x, y: int8): int8 {.magic: "MaxI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc max(x, y: int16): int16 {.magic: "MaxI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc max(x, y: int32): int32 {.magic: "MaxI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc max(x, y: int64): int64 {.magic: "MaxI", noSideEffect, ...raises: [], tags: [].}
The maximum value of two integers. Source   Edit  
proc max[T: not SomeFloat](x, y: T): T {.inline.}
Source   Edit  
proc max[T](x: openArray[T]): T
The maximum value of x. T needs to have a < operator. Source   Edit  
proc min(x, y: float32): float32 {.noSideEffect, inline, ...raises: [], tags: [].}
Source   Edit  
proc min(x, y: float64): float64 {.noSideEffect, inline, ...raises: [], tags: [].}
Source   Edit  
proc min(x, y: int): int {.magic: "MinI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc min(x, y: int8): int8 {.magic: "MinI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc min(x, y: int16): int16 {.magic: "MinI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc min(x, y: int32): int32 {.magic: "MinI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc min(x, y: int64): int64 {.magic: "MinI", noSideEffect, ...raises: [], tags: [].}
The minimum value of two integers. Source   Edit  
proc min[T: not SomeFloat](x, y: T): T {.inline.}
Source   Edit  
proc min[T](x: openArray[T]): T
The minimum value of x. T needs to have a < operator. Source   Edit  
proc `mod`(x, y: int): int {.magic: "ModI", noSideEffect, ...raises: [], tags: [].}

Computes the integer modulo operation (remainder).

This is the same as x - (x div y) * y.

Example:

assert (7 mod 5) == 2
assert (-7 mod 5) == -2
assert (7 mod -5) == 2
assert (-7 mod -5) == -2
Source   Edit  
proc `mod`(x, y: int8): int8 {.magic: "ModI", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc `mod`(x, y: int16): int16 {.magic: "ModI", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `mod`(x, y: int32): int32 {.magic: "ModI", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `mod`(x, y: int64): int64 {.magic: "ModI", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `mod`(x, y: uint): uint {.magic: "ModU", noSideEffect, ...raises: [], tags: [].}
Computes the integer modulo operation (remainder) for unsigned integers. This is the same as x - (x div y) * y. Source   Edit  
proc `mod`(x, y: uint8): uint8 {.magic: "ModU", noSideEffect, ...raises: [],
                                 tags: [].}
Source   Edit  
proc `mod`(x, y: uint16): uint16 {.magic: "ModU", noSideEffect, ...raises: [],
                                   tags: [].}
Source   Edit  
proc `mod`(x, y: uint32): uint32 {.magic: "ModU", noSideEffect, ...raises: [],
                                   tags: [].}
Source   Edit  
proc `mod`(x, y: uint64): uint64 {.magic: "ModU", noSideEffect, ...raises: [],
                                   tags: [].}
Source   Edit  
proc move[T](x: var T): T {.magic: "Move", noSideEffect, ...raises: [], tags: [].}
Source   Edit  
proc moveMem(dest, source: pointer; size: Natural) {.inline, ...gcsafe, locks: 0,
    ...tags: [], locks: 0, ...raises: [].}

Copies the contents from the memory at source to the memory at dest.

Exactly size bytes will be copied. The memory regions may overlap, moveMem handles this case appropriately and is thus somewhat more safe than copyMem. Like any procedure dealing with raw memory this is still unsafe, though.

Source   Edit  
proc new(t: typedesc): auto

Creates a new object of type T and returns a safe (traced) reference to it as result value.

When T is a ref type then the resulting type will be T, otherwise it will be ref T.

Source   Edit  
proc new[T](a: var ref T) {.magic: "New", noSideEffect, ...raises: [], tags: [].}
Creates a new object of type T and returns a safe (traced) reference to it in a. Source   Edit  
proc new[T](a: var ref T; finalizer: proc (x: ref T) {.nimcall.}) {.
    magic: "NewFinalize", noSideEffect, ...raises: [], tags: [].}

Creates a new object of type T and returns a safe (traced) reference to it in a.

When the garbage collector frees the object, finalizer is called. The finalizer may not keep a reference to the object pointed to by x. The finalizer cannot prevent the GC from freeing the object.

Note: The finalizer refers to the type T, not to the object! This means that for each object of type T the finalizer will be called!

Source   Edit  
proc newSeq[T](len = 0.Natural): seq[T]

Creates a new sequence of type seq[T] with length len.

Note that the sequence will be filled with zeroed entries. After the creation of the sequence you should assign entries to the sequence instead of adding them.

See also:

var inputStrings = newSeq[string](3)
assert len(inputStrings) == 3
inputStrings[0] = "The fourth"
inputStrings[1] = "assignment"
inputStrings[2] = "would crash"
#inputStrings[3] = "out of bounds"
Source   Edit  
proc newSeq[T](s: var seq[T]; len: Natural) {.magic: "NewSeq", noSideEffect,
    ...raises: [], tags: [].}

Creates a new sequence of type seq[T] with length len.

This is equivalent to s = @[]; setlen(s, len), but more efficient since no reallocation is needed.

Note that the sequence will be filled with zeroed entries. After the creation of the sequence you should assign entries to the sequence instead of adding them. Example:

var inputStrings: seq[string]
newSeq(inputStrings, 3)
assert len(inputStrings) == 3
inputStrings[0] = "The fourth"
inputStrings[1] = "assignment"
inputStrings[2] = "would crash"
#inputStrings[3] = "out of bounds"
Source   Edit  
proc newSeqOfCap[T](cap: Natural): seq[T] {.magic: "NewSeqOfCap", noSideEffect,
    ...raises: [], tags: [].}
Creates a new sequence of type seq[T] with length zero and capacity cap.
var x = newSeqOfCap[int](5)
assert len(x) == 0
x.add(10)
assert len(x) == 1
Source   Edit  
proc newSeqUninitialized[T: SomeNumber](len: Natural): seq[T]

Creates a new sequence of type seq[T] with length len.

Only available for numbers types. Note that the sequence will be uninitialized. After the creation of the sequence you should assign entries to the sequence instead of adding them.

var x = newSeqUninitialized[int](3)
assert len(x) == 3
x[0] = 10
Source   Edit  
proc newString(len: Natural): string {.magic: "NewString",
                                       importc: "mnewString", noSideEffect,
                                       ...raises: [], tags: [].}

Returns a new string of length len but with uninitialized content. One needs to fill the string character after character with the index operator s[i].

This procedure exists only for optimization purposes; the same effect can be achieved with the & operator or with add.