regex-wrapper: Types that can only be constructed if they match a regular expression

[ bsd3, data, library ] [ Propose Tags ]

Provides tooling for working with types whose values must match a regular expression provided in the type.


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Versions [faq] 0.1.0.0, 0.1.0.1 (info)
Change log CHANGELOG.md
Dependencies aeson, base (>=4.12.0.0 && <4.13), bytestring, containers, hashable, regex-tdfa, string-conv, text [details]
License BSD-3-Clause
Copyright (c) 2019 Luke Clifton
Author Luke Clifton
Maintainer lukec@themk.net
Category Data
Bug tracker https://github.com/luke-clifton/regex-wrapper/issues
Source repo head: git clone https://github.com/luke-clifton/regex-wrapper
Uploaded by lukec at Mon Nov 11 06:39:13 UTC 2019
Distributions NixOS:0.1.0.1
Downloads 51 total (51 in the last 30 days)
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Status Hackage Matrix CI
Docs available [build log]
Last success reported on 2019-11-11 [all 1 reports]

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Readme for regex-wrapper-0.1.0.1

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Experimental

This library allows you to create types that are guaranteed to contain a string that matches a given regular expression which is expressed at the type level.

newtype User = User (Matched String "^[a-zA-Z0-9]{4,15}$")

parseUser :: String -> Either (RegexError String) User
parseUser = fmap User . parseMatchedEither

prettyUser :: User -> String
prettyUser (User m) = asString m

main :: IO ()
main = do
    l <- getLine
    case parseUser l of
        Right user -> putStrLn $ "Hello, " ++ prettyUser user ++ "!"
        Left error -> putStrLn $ "Could not parse username: " ++ prettyRegexError  error
./prog
bad
Could not parse username: The input "bad" did not match the pattern ^[a-zA-Z0-9]{4,15}$
./prog
good
Hello, good!