pcre-heavy

Finally! A Haskell regular expressions library that does not suck.

• based on pcre-light, none of that regex-compat-pluggable-backend stuff
• takes and returns Stringables everywhere, use ANY STRING TYPE (String, ByteString, LByteString, Text, LText, FilePath) -- but you need a bit more type annotations than usual
• a QuasiQuoter for regexps that does compile time checking (BTW, vim2hs has correct syntax highlighting for that!)
• SEARCHES FOR MULTIPLE MATCHES! DOES REPLACEMENT!

Usage

{-# LANGUAGE QuasiQuotes #-}
import           Text.Regex.PCRE.Heavy

Matching

>>> "https://unrelenting.technology" =~ [re|^http.*|] :: Bool
True

In an if, you don't even need the annotation:

if "https://unrelenting.technology" =~ [re|^http.*|] then "YEP" else "NOPE"

Extracting matches (You can use any string type, not just String)

>>> "https://unrelenting.technology" =~ [re|^https?://([^\.]+)\..*|] :: Maybe [String]
Just ["https://unrelenting.technology","unrelenting"]

scan returns all matches (search)

>>> scan [re|\s*entry (\d+) (\w+)\s*&?|] " entry 1 hello  &entry 2 hi" :: [[String]]
[
  [" entry 1 hello  &", "1", "hello"]
, ["entry 2 hi",        "2", "hi"]
]

Replacement

sub replaces the first match, gsub replaces all matches.

-- You can use a Stringable type as the replacement...
>>> gsub [re|\d+|] "!!!NUMBER!!!" "Copyright (c) 2015 The 000 Group"
"Copyright (c) !!!NUMBER!!! The !!!NUMBER!!! Group"

-- or a (Stringable a => [a] -> a) function -- that will get the groups...
>>> gsub [re|%(\d+)(\w+)|] (\(d:w:_) -> "{" ++ d ++ " of " ++ w ++ "}" :: String) "Hello, %20thing"
"Hello, {20 of thing}"

-- or a (Stringable a => a -> a) function -- that will get the full match...
>>> gsub [re|-\w+|] (\x -> "+" ++ (reverse $ drop 1 x) :: String) "hello -world"
"hello +dlrow"

-- or a (Stringable a => a -> [a] -> a) function.
-- That will get both the full match and the groups.
-- I have no idea why you would want to use that, but that's there :-)

License

Copyright 2015 Greg V greg@unrelenting.technology
Available under the ISC license, see the COPYING file