README.md

funcynim

Utility library to ease functional programming in Nim.

This project focuses on maximum backend compatibility, that is:

• C
• C++
• Objective-C
• JavaScript
• NimScript (not tested yet)
• Compile time expressions in all the backends above

Installation

nimble install 'https://github.com/thenjip/funcynim'

Dependencies

• nim >= 1.6.0
• nim_curry >= 0.1.0

Documentation

• API

Overview

The Unit type

Adapting a procedure returning void

import pkg/funcynim/[unit]


proc println*(s: string): Unit =
  echo(s)
  #[
    No need for explicit return.
    Since "Unit" is a single valued type, default initialization has already
    initialized "result" to the only valid value.
  ]#

Procedure composition

func pow2[N: SomeNumber](n: N): N =
  n * n

proc debugPrintlnAndReturn[T](x: T): T =
  debugEcho(x)
  x

when isMainModule:
  import pkg/funcynim/[chain]
  import std/[sugar]

  const
    input = 4.Natural
    got = pow2[input.typeof()].chain(debugPrintlnAndReturn)(input)

  doAssert(got == input * input)

Procedure aliases for operators

discard operator

import pkg/funcynim/[ignore]
import std/[sequtils]

discard
  "abc"
    .`&`('\n')
    .filterIt(it == 'b')
"abc"
  .`&`('\n')
  .filterIt(it == 'b')
  .ignore()

if ...: else: ... expression as a proc

import pkg/funcynim/[fold, into, unit]
import std/[os, sugar]

paramCount()
  .`==`(0)
  .fold((_: Unit) => "no args", (_: Unit) => "got args")
  .into(s => echo(s))

Common math operators

import pkg/funcynim/[operators]

doAssert(5.plus(5).divInt(5) == 2)
doAssert(not true.logicOr(false).logicNot())

Currying

Thanks to nim_curry.

import pkg/funcynim/[curry, ignore, run, unit]
import std/[terminal]

proc writeLn(f: File; styles: set[Style]; self: string): Unit {.curry.} =
  f.styledWriteLine(styles, self)

writeLn(stdout)
  .with({styleUnderscore})
  .run("abc")
  .ignore()

Partial application

Not to be confused with currying.

import pkg/funcynim/[chain, operators, partialproc]

let f =
  partial(1 + ?:int) # (i: int) => 1 + i
  .chain(partial(1.mult(?_))) # (_: auto) => 1.mult(_)

doAssert(f(10) == 11)

And more

See documentation.