I'm making a parser for a DSL in Haskell using Alex + Happy. My DSL uses dice rolls as part of the possible expressions. Sometimes I have an expression that I want to parse that looks like: [some c...

I can not figure out the correct RegEx to use for parsing a text file and identifying paragraphs. What I currently have: [\n\n]+ Sample Text: Das Pensionat Klinger war bereits etwas zusamm...

I'm writing a toy language in haskell. I'm using Alex to generate a scanner. Every time I build my project with cabal, I get the following warnings: dist/build/optimiser/optimiser-tmp/Lexer.hs:465...

The source tree for happy contains AttrGrammarParser.ly and Parser.ly and the source tree for alex contains Scan.x. Yet, as far as I can tell in order to compile happy, we need to transform the .ly...

I'm learning to use Alex and Happy to write a small compiler. I want to maintain line and column information for my AST nodes so that I can provide meaningful error messages to the user. To illustr...

When creating either a Lexer.x or a Parser.y parser using the Alex lexer generator or the Happy parser generator, compiling those into Haskell files, and compiling those into object files, by defau...

In my current project I have a file Tokens.x that needs to be compiled to Tokens.hs by Alex. In my .cabal file I have listed Tokens in the other-modules section and cabal build happily creates the ...

I'm trying to learn using Alex + Happy to build parser, in particular I'm interested in learning to use the monad wrapper of Alex. I have already looked at the documentation of Alex and Happy but I...

I'm writing a compiler for a class I'm taking. The class isn't specifically Haskell but I'm using Haskell to write my compiler and interpreter. I have a cabal package setup to hopefully make it eas...

I'm working on a small Haskell project that needs to be able to lex a very small subset of strictly formed English in to tokens for semantic parsing. It's a very naïve natural language interface to...

I'm trying to understand Alex and lexers in general but I'm having trouble to run my lexer. I wrote lexers in "basic" and "posn" wrappers but I couldn't in "monad" wrapper. I think I have to use m...

Mixing the lexer and parsing phases in one phase sometimes makes Parsec parsers less readable but also slows them down. One solution is to use Alex as a tokenizer and then Parsec as a parser of the...