Iterates through a container and checks if every item fulfills the predicate.

See also:

• allIt template
• any proc

Example:

let numbers = @[1, 4, 5, 8, 9, 7, 4]
assert all(numbers, proc (x: int): bool = x < 10) == true
assert all(numbers, proc (x: int): bool = x < 9) == false

Iterates through a container and checks if at least one item fulfills the predicate.

See also:

• anyIt template
• all proc

Example:

let numbers = @[1, 4, 5, 8, 9, 7, 4]
assert any(numbers, proc (x: int): bool = x > 8) == true
assert any(numbers, proc (x: int): bool = x > 9) == false

Example:

var message: string
apply([0, 1, 2, 3, 4], proc(item: int) = message.addInt item)
assert message == "01234"

Applies op to every item in s modifying it directly.

Note that the container s must be declared as a var and it is required for your input and output types to be the same, since s is modified in-place. The parameter function takes and returns a T type variable.

See also:

• applyIt template
• map proc

Example:

var a = @["1", "2", "3", "4"]
apply(a, proc(x: string): string = x & "42")
assert a == @["142", "242", "342", "442"]

Applies op to every item in s, modifying it directly.

Note that the container s must be declared as a var, since s is modified in-place. The parameter function takes a var T type parameter.

See also:

• applyIt template
• map proc

Example:

var a = @["1", "2", "3", "4"]
apply(a, proc(x: var string) = x &= "42")
assert a == @["142", "242", "342", "442"]

Takes several sequences' items and returns them inside a new sequence. All sequences must be of the same type.

See also:

• distribute func for a reverse operation

Example:

let
  s1 = @[1, 2, 3]
  s2 = @[4, 5]
  s3 = @[6, 7]
  total = concat(s1, s2, s3)
assert total == @[1, 2, 3, 4, 5, 6, 7]

Example:

let
  a = @[1, 2, 2, 3, 2, 4, 2]
  b = "abracadabra"
assert count(a, 2) == 4
assert count(a, 99) == 0
assert count(b, 'r') == 2

Example:

let
  s = @[1, 2, 3]
  total = s.cycle(3)
assert total == @[1, 2, 3, 1, 2, 3, 1, 2, 3]

Returns a new sequence without duplicates.

Setting the optional argument isSorted to true (default: false) uses a faster algorithm for deduplication.

Example:

let
  dup1 = @[1, 1, 3, 4, 2, 2, 8, 1, 4]
  dup2 = @["a", "a", "c", "d", "d"]
  unique1 = deduplicate(dup1)
  unique2 = deduplicate(dup2, isSorted = true)
assert unique1 == @[1, 3, 4, 2, 8]
assert unique2 == @["a", "c", "d"]

Deletes the items s[slice], raising IndexDefect if the slice contains elements out of range.

This operation moves all elements after s[slice] in linear time.

Example:

var a = @[10, 11, 12, 13, 14]
doAssertRaises(IndexDefect): a.delete(4..5)
assert a == @[10, 11, 12, 13, 14]
a.delete(4..4)
assert a == @[10, 11, 12, 13]
a.delete(1..2)
assert a == @[10, 13]
a.delete(1..<1) # empty slice
assert a == @[10, 13]

Splits and distributes a sequence s into num sub-sequences.

Returns a sequence of num sequences. For some input values this is the inverse of the concat func. The input sequence s can be empty, which will produce num empty sequences.

If spread is false and the length of s is not a multiple of num, the func will max out the first sub-sequence with 1 + len(s) div num entries, leaving the remainder of elements to the last sequence.

On the other hand, if spread is true, the func will distribute evenly the remainder of the division across all sequences, which makes the result more suited to multithreading where you are passing equal sized work units to a thread pool and want to maximize core usage.

Example:

let numbers = @[1, 2, 3, 4, 5, 6, 7]
assert numbers.distribute(3) == @[@[1, 2, 3], @[4, 5], @[6, 7]]
assert numbers.distribute(3, false) == @[@[1, 2, 3], @[4, 5, 6], @[7]]
assert numbers.distribute(6)[0] == @[1, 2]
assert numbers.distribute(6)[1] == @[3]

Returns a new sequence with all the items of s that fulfill the predicate pred (a function that returns a bool).

Instead of using map and filter, consider using the collect macro from the sugar module.

See also:

• sugar.collect macro
• filterIt template
• filter iterator
• keepIf proc for the in-place version

Example:

let
  colors = @["red", "yellow", "black"]
  f1 = filter(colors, proc(x: string): bool = x.len < 6)
  f2 = filter(colors, proc(x: string): bool = x.contains('y'))
assert f1 == @["red", "black"]
assert f2 == @["yellow"]

Inserts items from src into dest at position pos. This modifies dest itself, it does not return a copy.

Note that the elements of src and dest must be of the same type.

Example:

var dest = @[1, 1, 1, 1, 1, 1, 1, 1]
let
  src = @[2, 2, 2, 2, 2, 2]
  outcome = @[1, 1, 1, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1]
dest.insert(src, 3)
assert dest == outcome

Keeps the items in the passed sequence s if they fulfill the predicate pred (a function that returns a bool).

Note that s must be declared as a var.

Similar to the filter proc, but modifies the sequence directly.

See also:

• keepItIf template
• filter proc

Example:

var floats = @[13.0, 12.5, 5.8, 2.0, 6.1, 9.9, 10.1]
keepIf(floats, proc(x: float): bool = x > 10)
assert floats == @[13.0, 12.5, 10.1]

Returns a new sequence with the results of the op proc applied to every item in the container s.

Since the input is not modified, you can use it to transform the type of the elements in the input container.

Instead of using map and filter, consider using the collect macro from the sugar module.

See also:

• sugar.collect macro
• mapIt template
• apply proc for the in-place version

Example:

let
  a = @[1, 2, 3, 4]
  b = map(a, proc(x: int): string = $x)
assert b == @["1", "2", "3", "4"]

Example:

let
  a = @[1, 2, 3, 4]
  b = @[6, 5, 4, 3]
  c = [2, -7, 8, -5]
  d = "ziggy"
assert maxIndex(a) == 3
assert maxIndex(b) == 0
assert maxIndex(c) == 2
assert maxIndex(d) == 0

Example:

let
  a = @[1, 2, 3, 4]
  b = @[6, 5, 4, 3]
  c = [2, -7, 8, -5]
  d = "ziggy"
assert minIndex(a) == 0
assert minIndex(b) == 3
assert minIndex(c) == 1
assert minIndex(d) == 2

Example:

let
  total = repeat(5, 3)
assert total == @[5, 5, 5]

Example:

let
  zipped = @[(1, 'a'), (2, 'b'), (3, 'c')]
  unzipped1 = @[1, 2, 3]
  unzipped2 = @['a', 'b', 'c']
assert zipped.unzip() == (unzipped1, unzipped2)
assert zip(unzipped1, unzipped2).unzip() == (unzipped1, unzipped2)

Returns a new sequence with a combination of the two input containers.

The input containers can be of different types. If one container is shorter, the remaining items in the longer container are discarded.

Note: For Nim 1.0.x and older version, zip returned a seq of named tuples with fields a and b. For Nim versions 1.1.x and newer, zip returns a seq of unnamed tuples.

Example:

let
  short = @[1, 2, 3]
  long = @[6, 5, 4, 3, 2, 1]
  words = @["one", "two", "three"]
  letters = "abcd"
  zip1 = zip(short, long)
  zip2 = zip(short, words)
assert zip1 == @[(1, 6), (2, 5), (3, 4)]
assert zip2 == @[(1, "one"), (2, "two"), (3, "three")]
assert zip1[2][0] == 3
assert zip2[1][1] == "two"
let
  zip3: seq[tuple[num: int, letter: char]] = zip(long, letters)
assert zip3 == @[(6, 'a'), (5, 'b'), (4, 'c'), (3, 'd')]
assert zip3[0].letter == 'a'

Iterates through a container s and yields every item that fulfills the predicate pred (a function that returns a bool).

Instead of using map and filter, consider using the collect macro from the sugar module.

See also:

• sugar.collect macro
• filter proc
• filterIt template

Example:

let numbers = @[1, 4, 5, 8, 9, 7, 4]
var evens = newSeq[int]()
for n in filter(numbers, proc (x: int): bool = x mod 2 == 0):
  evens.add(n)
assert evens == @[4, 8, 4]

Example:

let x = mapLiterals([0.1, 1.2, 2.3, 3.4], int)
doAssert x is array[4, int]
doAssert x == [int(0.1), int(1.2), int(2.3), int(3.4)]

Example:

let a = mapLiterals((1.2, (2.3, 3.4), 4.8), int)
let b = mapLiterals((1.2, (2.3, 3.4), 4.8), int, nested=false)
assert a == (1, (2, 3), 4)
assert b == (1, (2.3, 3.4), 4)

let c = mapLiterals((1, (2, 3), 4, (5, 6)), `$`)
let d = mapLiterals((1, (2, 3), 4, (5, 6)), `$`, nested=false)
assert c == ("1", ("2", "3"), "4", ("5", "6"))
assert d == ("1", (2, 3), "4", (5, 6))

Iterates through a container and checks if every item fulfills the predicate.

Unlike the all proc, the predicate needs to be an expression using the it variable for testing, like: allIt("abba", it == 'a').

See also:

• all proc
• anyIt template

Example:

let numbers = @[1, 4, 5, 8, 9, 7, 4]
assert numbers.allIt(it < 10) == true
assert numbers.allIt(it < 9) == false

Iterates through a container and checks if at least one item fulfills the predicate.

Unlike the any proc, the predicate needs to be an expression using the it variable for testing, like: anyIt("abba", it == 'a').

See also:

• any proc
• allIt template

Example:

let numbers = @[1, 4, 5, 8, 9, 7, 4]
assert numbers.anyIt(it > 8) == true
assert numbers.anyIt(it > 9) == false

Convenience template around the mutable apply proc to reduce typing.

The template injects the it variable which you can use directly in an expression. The expression has to return the same type as the elements of the sequence you are mutating.

In order for a type T to be used with applyIt, an mitems iterator of the form iterator mitems(x: var T): var ... must be present.

See also:

• apply proc
• mapIt template

Example:

var nums = @[1, 2, 3, 4]
nums.applyIt(it * 3)
assert nums[0] + nums[3] == 15

Returns a count of all the items that fulfill the predicate.

The predicate needs to be an expression using the it variable for testing, like: countIt(@[1, 2, 3], it > 2).

Example:

let numbers = @[-3, -2, -1, 0, 1, 2, 3, 4, 5, 6]
iterator iota(n: int): int =
  for i in 0..<n: yield i
assert numbers.countIt(it < 0) == 3
assert countIt(iota(10), it < 2) == 2

Returns a new sequence with all the items of s that fulfill the predicate pred.

Unlike the filter proc and filter iterator, the predicate needs to be an expression using the it variable for testing, like: filterIt("abcxyz", it == 'x').

Instead of using mapIt and filterIt, consider using the collect macro from the sugar module.

See also:

• sugar.collect macro
• filter proc
• filter iterator

Example:

let
  temperatures = @[-272.15, -2.0, 24.5, 44.31, 99.9, -113.44]
  acceptable = temperatures.filterIt(it < 50 and it > -10)
  notAcceptable = temperatures.filterIt(it > 50 or it < -10)
assert acceptable == @[-2.0, 24.5, 44.31]
assert notAcceptable == @[-272.15, 99.9, -113.44]

Template to fold a sequence from left to right, returning the accumulation.

This version of foldl gets a starting parameter. This makes it possible to accumulate the sequence into a different type than the sequence elements.

The operation parameter should be an expression which uses the variables a and b for each step of the fold. The first parameter is the start value (the first a) and therefor defines the type of the result.

See also:

• foldr template

Example:

let
  numbers = @[0, 8, 1, 5]
  digits = foldl(numbers, a & (chr(b + ord('0'))), "")
assert digits == "0815"

Template to fold a sequence from left to right, returning the accumulation.

The sequence is required to have at least a single element. Debug versions of your program will assert in this situation but release versions will happily go ahead. If the sequence has a single element it will be returned without applying operation.

The operation parameter should be an expression which uses the variables a and b for each step of the fold. Since this is a left fold, for non associative binary operations like subtraction think that the sequence of numbers 1, 2 and 3 will be parenthesized as (((1) - 2) - 3).

See also:

• foldl template with a starting parameter
• foldr template

Example:

let
  numbers = @[5, 9, 11]
  addition = foldl(numbers, a + b)
  subtraction = foldl(numbers, a - b)
  multiplication = foldl(numbers, a * b)
  words = @["nim", "is", "cool"]
  concatenation = foldl(words, a & b)
  procs = @["proc", "Is", "Also", "Fine"]


func foo(acc, cur: string): string =
  result = acc & cur

assert addition == 25, "Addition is (((5)+9)+11)"
assert subtraction == -15, "Subtraction is (((5)-9)-11)"
assert multiplication == 495, "Multiplication is (((5)*9)*11)"
assert concatenation == "nimiscool"
assert foldl(procs, foo(a, b)) == "procIsAlsoFine"

Template to fold a sequence from right to left, returning the accumulation.

The sequence is required to have at least a single element. Debug versions of your program will assert in this situation but release versions will happily go ahead. If the sequence has a single element it will be returned without applying operation.

The operation parameter should be an expression which uses the variables a and b for each step of the fold. Since this is a right fold, for non associative binary operations like subtraction think that the sequence of numbers 1, 2 and 3 will be parenthesized as (1 - (2 - (3))).

See also:

• foldl template
• foldl template with a starting parameter

Example:

let
  numbers = @[5, 9, 11]
  addition = foldr(numbers, a + b)
  subtraction = foldr(numbers, a - b)
  multiplication = foldr(numbers, a * b)
  words = @["nim", "is", "cool"]
  concatenation = foldr(words, a & b)
assert addition == 25, "Addition is (5+(9+(11)))"
assert subtraction == 7, "Subtraction is (5-(9-(11)))"
assert multiplication == 495, "Multiplication is (5*(9*(11)))"
assert concatenation == "nimiscool"

Keeps the items in the passed sequence (must be declared as a var) if they fulfill the predicate.

Unlike the keepIf proc, the predicate needs to be an expression using the it variable for testing, like: keepItIf("abcxyz", it == 'x').

See also:

• keepIf proc
• filterIt template

Example:

var candidates = @["foo", "bar", "baz", "foobar"]
candidates.keepItIf(it.len == 3 and it[0] == 'b')
assert candidates == @["bar", "baz"]

Returns a new sequence with the results of the op proc applied to every item in the container s.

Since the input is not modified you can use it to transform the type of the elements in the input container.

The template injects the it variable which you can use directly in an expression.

Instead of using mapIt and filterIt, consider using the collect macro from the sugar module.

See also:

• sugar.collect macro
• map proc
• applyIt template for the in-place version

Example:

let
  nums = @[1, 2, 3, 4]
  strings = nums.mapIt($(4 * it))
assert strings == @["4", "8", "12", "16"]

Creates a new seq of length len, calling init to initialize each value of the seq.

Useful for creating "2D" seqs - seqs containing other seqs or to populate fields of the created seq.

Example:

## Creates a seq containing 5 bool seqs, each of length of 3.
var seq2D = newSeqWith(5, newSeq[bool](3))
assert seq2D.len == 5
assert seq2D[0].len == 3
assert seq2D[4][2] == false

## Creates a seq with random numbers
import std/random
var seqRand = newSeqWith(20, rand(1.0))
assert seqRand[0] != seqRand[1]

Example:

let
  myRange = 1..5
  mySet: set[int8] = {5'i8, 3, 1}
assert typeof(myRange) is HSlice[system.int, system.int]
assert typeof(mySet) is set[int8]

let
  mySeq1 = toSeq(myRange)
  mySeq2 = toSeq(mySet)
assert mySeq1 == @[1, 2, 3, 4, 5]
assert mySeq2 == @[1'i8, 3, 5]