I'm using happyJS and use the regex underneath for phone validation phone: function (val) { return /^(?:[0-9]+$)/.test(val); } However this ONLY allows numbers. I want the user to be able to e...

I have a grammar that, depending on the order of productions, happy reports 3 reduce/reduce conflicts or none. The minimal example I can find is: %tokentype {Token} %token int { Int } '-' { Neg ...

I am attempting to build GHC from source following this page. When installing dependencies, I had to install happy and alex: $ cabal install alex happy Resolving dependencies... Configuring alex-3...

I have two snippets of Happy code here, one that uses normal precedence rules, and one that uses context-dependent precedence rules (both of which are described here). Normal: %left '+' %left '*'...

As part of my compiler, I need alex and happy to run as part of my build process. How does Stack support this scenario? Bonus: how can I register alex and happy as compile-time dependencies?

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...

I've been trying to get happy to install correctly for the past couple days, and while I found it challenging to get cabal install happy to not just error (by installing happy-1.19 with apt-get and...

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've trying to do cabal install hoogle but there is a hickup with the haskell-src-exts-1.13.5 dependency: Configuring haskell-src-exts-1.13.5... setup: The program happy version >=1.17 is requi...

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 am going to write a parser of verilog (or vhdl) language and will do a lot of manipulations (sort of transformations) of the parsed data. I intend to parse really big files (full Verilog designs,...

To learn how to write and parse a context-free grammar I want to choose a tool. For Haskell, there are two big options: Happy, which generates a parser from a grammar description and *Parsec, which...

I am using Happy to generate a parser. I have found that when I give it tokens which match part of the grammar at a lower level than the top level (such as giving it an expression on it's own, tha...

So I am trying to implement a pretty simple grammar for one-line statements: # Grammar c : Character c [a-z0-9-] (v) : Vowel (= [a,e,u,i,o]) (c) : Consonant (?) : Any character (incl. number)...