We have a regex tutorial at http://tutorial.regex.uk.

This module just provides a brief overview of the regex package. You will need to import one of the API modules of which there is a choice which will depend upon two factors:

• Which flavour of regular expression do you want to use? If you need Posix flavour REs then you will want the TDFA modules, otherwise its PCRE for Perl-style REs.
• What type of text do you want to match: (slow) Strings, ByteString, ByteString.Lazy, Text, Text.Lazy or the anachronistic Seq Char or indeed some good old-fashioned polymorphic operators?

While we aim to provide all combinations of these choices, some of them are currently not available. In the regex package we have:

• Text.RE.TDFA.ByteString
• Text.RE.TDFA.ByteString.Lazy
• Text.RE.ZeInternals.TDFA
• Text.RE.TDFA.Sequence
• Text.RE.TDFA.String
• Text.RE.TDFA.Text
• Text.RE.TDFA.Text.Lazy
• Text.RE.TDFA

The PCRE modules are contained in the separate regex-with-pcre package:

• Text.RE.PCRE.ByteString
• Text.RE.PCRE.ByteString.Lazy
• Text.RE.ZeInternals.PCRE
• Text.RE.PCRE.Sequence
• Text.RE.PCRE.String
• Text.RE.PCRE

For more specialist applications we have the following:

• Text.RE.REOptions for specifying back-end specific options;
• Text.RE.Replace for the full replace toolkit;
• Text.RE.TestBench for building up, testing and doumenting; macro environments for use in REs;
• Text.RE.Tools for an AWK-like text-processing toolkit.

Class IsRegex re t provides methods for matching the t type for the re back end as well as compiling REs from t to re and getting the source t back again. The Replace superclass of IsRegex contains a useful toolkit for converting between t and String abd Text.