haskell/happy

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The Happy parser generator for Haskell

Stars: 322
Forks: 86
Open beginner issues: 0
Indexed issues: 40

Dominant language: Haskell
License: No license data
Last GitHub push: Apr 2, 2026
Latest indexed: Sep 14, 2026
Contributing guide: Contributing guide
Code of conduct: No code of conduct
Beginner labels: No beginner labels indexed
PR merge metrics: No merged PRs in 30d

Open All

40 open issues indexed

GLR feature needs to be usable without command line args Open

haskell/happy#3 · 4 comments · 3 reactions · 0 assignees · Indexed Sep 14, 2026
Incremental parsing API and improved error handling Open

haskell/happy#71 · 1 comment · 2 reactions · 0 assignees · Indexed Sep 14, 2026
Use Elkhound's techniques to optimize the GLR mode Open

re: GLR

haskell/happy#72 · 4 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Parse error on empty %token list Open

haskell/happy#107 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Parameterised Productions - Termination Open

haskell/happy#118 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Support Mid-rule actions Open

haskell/happy#129 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Example of a monaduserstate with a lexer and a parser Open

haskell/happy#132 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Unused states Open

haskell/happy#138 · 3 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Add examples and test for type signatures on parametrized productions Open

haskell/happy#147 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Support inlining of non-terminals, as Menhir does Open

haskell/happy#148 · 9 comments · 4 reactions · 0 assignees · Indexed Sep 14, 2026
Happy and template haskell Open

haskell/happy#149 · 9 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
hGetContent says invalid byte sequence on Windows, non-English locale Open

haskell/happy#157 · 4 comments · 1 reaction · 0 assignees · Indexed Sep 14, 2026
Happy should error out on duplicate productions Open

haskell/happy#158 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Happy parse error messages should include more information Open

haskell/happy#159 · 1 comment · 4 reactions · 0 assignees · Indexed Sep 14, 2026
Consider a recusive ascent/descent backend Open

haskell/happy#167 · 12 comments · 5 reactions · 0 assignees · Indexed Sep 14, 2026
GLR_Lib.hs "Couldn't match expected type ‘Bool’ with actual type ‘Int#’" Open

haskell/happy#173 · 5 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
GLR: generated file `*Data.hs` doesn't declare its OPTIONS and LANGUAGE pragmas Open

haskell/happy#183 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Default backend should generate TemplateHaskell and write that to a file Open

haskell/happy#190 · 3 comments · 1 reaction · 0 assignees · Indexed Sep 14, 2026
conflicts between documentation Open

haskell/happy#194 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Examples don't work Open

haskell/happy#197 · 4 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Support parser rule includes/modules Open

haskell/happy#198 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Old TODO Open

haskell/happy#208 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
inclarity in threaded lexer docs leads to confusing failure Open

haskell/happy#227 · 3 comments · 1 reaction · 0 assignees · Indexed Sep 14, 2026
Documentation: Constraints on Parser Monad Open

haskell/happy#231 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Implement something like "Principled parsing for indentation-sensitive languages" Open

haskell/happy#235 · 8 comments · 1 reaction · 0 assignees · Indexed Sep 14, 2026
Split up CLI into packages Open

haskell/happy#239 · 2 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Incremental parsing Open

haskell/happy#240 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Idea: Backend for generating railroad diagrams Open

haskell/happy#244 · 3 comments · 3 reactions · 0 assignees · Indexed Sep 14, 2026
Grammar that bison/byacc reports 35 reduce/reduce conflicts but happy none Open

haskell/happy#260 · 5 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Expected list of tokens provided by `%errordefaulthandler explist` only lists shift tokens of most recent state Open

re: building happy re: error handler

haskell/happy#265 · 3 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Happy-generated code fails with `Internal Happy error` with `-XStrictData` Open

documentation enhancement

haskell/happy#273 · 17 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Ignore individual warnings in generated code, rather than all warnings. Open

enhancement

haskell/happy#294 · 0 comments · 1 reaction · 0 assignees · Indexed Sep 14, 2026
Code blocks should strip alignment of opening brace Open

haskell/happy#305 · 0 comments · 1 reaction · 0 assignees · Indexed Sep 14, 2026
`Fin n` for array indexes? Open

haskell/happy#313 · 6 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Explicitly set text encoding to utf-8? Open

haskell/happy#337 · 1 comment · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Feature Request: Add ability to generate lazily generated list of data structures. Open

haskell/happy#338 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Strict mode is not in fact strict Open

haskell/happy#346 · 4 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
reduce/reduce conflict handling order: difference in documentation vs. code Open

haskell/happy#350 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Happy and `haskell-src-exts` differ by shift/reduce conflicts Open

haskell/happy#354 · 3 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026
Quoted terminals are not escaped in --glr mode Open

haskell/happy#356 · 0 comments · 0 reactions · 0 assignees · Indexed Sep 14, 2026

haskell/happy

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