Haskell Regex Evaluator

module Main where

import Regex

main :: IO ()
main = do
    print $ test "foo" "foo"
    print $ test "(bar)+" "barbar"
    print $ test "bar+" "barrrr"
    print $ test "foo|(bar)+" "fobarbar"
    print $ test "(foo)*bar(baz)+" "barbazbaz"

all samples result in True

Supported features:

• matching of single chars
• concatenated regexes by appending them together
• the | between any two regexes
• the * operator on any potentially nested regex
• the + operator on any potentially nested regex
• the ? operator on any potentially nested regex
• nested regexes with ( ) to apply the operators to complex regexes

Implementation details

Lexing and parsing happens with Alex and Happy.

The eval function uses a State monand with a Set of remainders as the state and a Bool as the value. (This migth change for the implementation of capture groups).