lazyseq

Lazy evaluated sequences

Pure Nim score 15/100 · tests present · no docs generated

Summary

Latest Version 0.1.0
License MIT
CI Status Failing
Downloads 0
Last Indexed 2026-09-01 07:18

Tags

lazy sequences infinite functional map reduce zip filter

Authors

  • lazyseq authors

Installation

nimble install lazyseq
choosenim install lazyseq
git clone https://github.com/markspanbroek/nim-lazyseq

OS Compatibility

Platform Linux macOS Windows FreeBSD OpenBSD NetBSD Android iOS WASM Embedded
lazyseq ✓ ✓ ✓ - - - - - - -

Dependencies

Package Version Optional
nim >= 1.4.2 & < 2.0.0 No

Source

Repository https://github.com/markspanbroek/nim-lazyseq
Homepage https://github.com/markspanbroek/nim-lazyseq
Registry Source nimble_official

README

Lazy Sequences

Lazy evaluated sequences, that can be infinitely long. Includes operations such as map, filter, reduce and zip.

Installation

Use the Nimble package manager to add lazyseq to an existing project. Add the following to its .nimble file:

requires "lazyseq >= 0.1.0 & < 0.2.0"

Examples

Turn a normal sequence into a lazy sequence.

@[1, 2, 3].lazy

Lazy evaluate the reverse of a normal seq.

@[1, 2, 3].reverse  # equals @[3, 2, 1].lazy

Evaluate a lazy sequence into a normal seq (don't do this with infinite sequences).

@[1, 2, 3].reverse.toSeq

An infinitely repeated value.

42.repeat()

Take the first n elements of a lazy sequence:

42.repeat().take(5)  # equals @[42, 42, 42, 42, 42].lazy

Concatenate two lazy sequences:

@[1, 2].lazy & @[3, 4].lazy  # equals @[1, 2, 3, 4].lazy

Combine (zip) two lazy sequences:

zip(@[1, 2].lazy, @["a", "b"].lazy)  # equals @[(1, "a"), (2, "b")].lazy

Transform (map) a lazy sequence into another:

@[1, 2, 3].lazy.map(x => $x)  # equals @["1", "2", "3"].lazy

Filter a lazy sequence:

@[1, 2, 3, 4].lazy.filter(x => (x mod 2 == 0))  # equals @[2, 4].lazy

Combine (reduce) all elements of a sequence:

@[1, 2, 3, 4].lazy.reduce(0, (x, y) => x + y)  # equals 10
@[1, 2, 3, 4].lazy.reduce(1, (x, y) => x * y)  # equals 24
@[1, 2, 3, 4].lazy.reduce("", (x, y) => x & $y)  # equals "1234"

Generate an infinite sequence:

let naturals = generate[int]:
  var n = 0
  while true:
    yield n
    inc n