*Main> let re = listToSequence [ hello, oneOrMore world, hello ]
*Main> re
hello(world)+hello
I am looking for suggestions on how I could encode the anchors - ^ and $ and also how I could refer to captures. My goal is to be able to extend the idea to create an EDSL that could be used to build Perl tasks - such as filters, report generators etc
Why not just go with anchorHead and anchorTail or similar? And a capture could simply be
capture name regularExpression
where name can be an Int or support the newer named capture syntaxes. I'm not sure I would bother with fancy symbols; if anything, I might in your position go back to the old v8 regular expressions (or rather Henry Spencer's unencumbered reimplementation) and use the symbolic names from that; they were actually virtual machine opcodes.
(Or even
capture (Maybe name) regularExpression
and (capture Nothing ...) could represent grouping. That's certainly how many actual RE implementations define it.)
Arguably this could be seen as a pointless exercise because I could chose to do the scripting in Haskell itself but I have a practical problem that I have to deal with clusters that have a little dated version of Linux where I could not really build the
(Don't even get me started on Linux backward incompatibility... I spent years fighting that crap, it's one thing I do not at all miss from my old job.)