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https://github.com/agrafix/validate-input

A small Haskell combinator library that provides a simple way of validating user provided data structures
https://github.com/agrafix/validate-input

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A small Haskell combinator library that provides a simple way of validating user provided data structures

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validate-input
=====

[![Build Status](https://travis-ci.org/agrafix/validate-input.svg)](https://travis-ci.org/agrafix/validate-input)
[![Hackage](https://img.shields.io/hackage/v/validate-input.svg)](http://hackage.haskell.org/package/validate-input)

## Intro

Hackage: [validate-input](http://hackage.haskell.org/package/validate-input)
Stackage: [validate-input](https://www.stackage.org/package/validate-input)

Input validation combinator library

## Library Usage Example

```haskell
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes #-}
import Data.Validator
import qualified Data.Text as T

data Example
= Example
{ ex_username :: T.Text
, ex_dogs :: Int
, ex_friendName :: Maybe T.Text
} deriving (Show)

data ExampleChecked
= ExampleChecked
{ exc_username :: T.Text
, exc_dogs :: Int
, exc_friendName :: T.Text
} deriving (Show)

main :: IO ()
main =
do putStrLn "Check results:"
print example

checkUsername :: Monad m => ValidationRuleT String m T.Text
checkUsername =
lengthBetween 3 12 "Should between 3 and 12 chars"
>=> matchesRegex [re|^[A-za-z0-9]+$|] "only alpha num"

checkNumber :: Monad m => ValidationRuleT String m Int
checkNumber =
smallerThan 5 "No more than 5 dogs allowed"

checkExample :: Monad m => TransValidationRuleT String m Example ExampleChecked
checkExample e =
ExampleChecked
<$> checkUsername (ex_username e)
<*> checkNumber (ex_dogs e)
<*> requiredValue "You must provide a friend name!" (ex_friendName e)

example :: Either String ExampleChecked
example =
runValidator checkExample $
Example
{ ex_username = "alex"
, ex_dogs = 23
, ex_friendName = Nothing
}

```

## Install

* Using cabal: `cabal install validate-input`
* Using Stack: `stack install validate-input`
* From Source (cabal): `git clone https://github.com/agrafix/validate-input.git && cd validate-input && cabal install`
* From Source (stack): `git clone https://github.com/agrafix/validate-input.git && cd validate-input && stack build`

## Misc

### Supported GHC Versions

* 8.8.4

### License

Released under the MIT license.
(c) 2015-2021 Alexander Thiemann