tfausak/flow

:droplet: Write more understandable Haskell.

Source code at GitHub https://hackage.haskell.org/package/flow

{
  "createdAt": "2015-04-01T22:12:06Z",
  "defaultBranch": "main",
  "description": ":droplet: Write more understandable Haskell.",
  "fullName": "tfausak/flow",
  "homepage": "https://hackage.haskell.org/package/flow",
  "language": "Haskell",
  "name": "flow",
  "pushedAt": "2025-11-25T19:34:57Z",
  "stargazersCount": 203,
  "topics": [
    "haskell",
    "operator"
  ],
  "updatedAt": "2025-11-25T19:35:01Z",
  "url": "https://github.com/tfausak/flow"
}

[Flow][]

Write more understandable Haskell.

Flow is a package that provides functions and operators for writing more understandable Haskell. It is an alternative to some common idioms like [($)][] for function application and [(.)][] for function composition.

Requirements
Installation
Usage
- Cheat sheet

Requirements

Flow requires a Haskell compiler. It is tested with recent versions of GHC, but older or different compilers should be acceptable. For installation with Cabal, Flow requires at least Cabal 2.2.

Installation

To add Flow as a dependency to your package, add it to your Cabal file.

build-depends: flow ==2.0.*

Usage

Flow is designed to be imported unqualified. It does not export anything that conflicts with [the base package][].

import Flow

Cheat sheet

Flow	Base
`x \|> f`	`x & f`
`f <\| x`	`f $ x`
`apply x f`	`f x`
`f .> g`	`f >>> g`
`g <. f`	`g . f`
`compose f g x`	`g (f x)`
`x !> f`	-
`f <! x`	`f $! x`
`apply' x f`	`seq x (f x)`

Converting existing code

If you want to uniformly use flow operators you can use [HLint] with the hlint-flow.yaml file. For easy use, it is best to extract the hlint-flow.yaml to your project directory and do

> hlint -h hlint-flow.yaml <source file>

> hlint --git -h hlint-flow.yaml

to check all Haskell source tracked by git.

For more information about Flow, please read [the Haddock documentation][].

[HLint] !: https://github.com/ndmitchell/hlint [Flow] !: http://taylor.fausak.me/flow/ [($)] !: http://hackage.haskell.org/package/base-4.8.0.0/docs/Prelude.html#v:-36- [(.)] !: http://hackage.haskell.org/package/base-4.8.0.0/docs/Prelude.html#v:. [the base package] !: http://hackage.haskell.org/package/base [the haddock documentation] !: https://hackage.haskell.org/package/flow/docs/Flow.html