foreach

A sugary for loop with syntax for typechecking loop variables

Pure Nim score 30/100 · tests present · docs generated

Summary

Latest Version 1.0.2
License MIT
CI Status Failing
Downloads 0
Last Indexed 2026-09-03 07:23

Tags

macro syntax sugar

Authors

  • disruptek

Installation

nimble install foreach
choosenim install foreach
git clone https://github.com/disruptek/foreach

OS Compatibility

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

Dependencies

Package Version Optional
nim >= 0.20.0 No

Source

Repository https://github.com/disruptek/foreach
Homepage https://github.com/disruptek/foreach
Documentation View Documentation
Registry Source nimble_official

README

foreach

A sugary for loop macro with syntax for typechecking loop variables. I've found that this syntax is as helpful for documentation as it is for eliminating errors.

Example

import foreach

let a = [1, 2, 3]

foreach n in a.items of int:
  echo n, " is an int"

or

import json
import foreach

let j = %* {
  "one": 1,
  "two": "2",
}

foreach k, v in j.pairs of string and JsonNode:
    echo k, " is a string"
    echo v, " is a JsonNode"

but this will now fail at compile-time:

import json
import foreach

let j = %* {
  "one": 1,
  "two": "2",
}

# Error: loop variable `v` isn't a `string`
foreach k, v in j.pairs of string and string:
  echo k, " is a string"
  echo v, " is a string"

and you can use this to validate tuple field order/names:

import json
import foreach

type
  JsonKeyValue = tuple[key: string; value: JsonNode]

let j = %* {
  "one": 1,
  "two": "2",
}

# Error: loop variable `pair` isn't a `JsonKeyValue`
foreach pair in j.pairs of JsonKeyValue:
  assert pair.key is string

and for convenience, these compile to "normal" for loops:

import json
import foreach

let j = %* {
  "one": 1,
  "two": "2",
}

foreach k in 1 .. 5:
  assert k > 0

foreach k, v in j.pairs:
  echo k, " is a string"
  echo v, " isn't really a string"