Initialize the project

[fizruk]

This initializes the Haskell part of the project. In particular, the following is added:

• eo-phi-normalizer Haskell package
  • grammar/EO/Phi/Syntax.cf contains the EBNF for 𝜑-calculus, based on Phi.g4 grammar. Currently it contains some shift/reduce and reduce/reduce conflicts that need to be resolved (or we could use GLR mode for Happy, but I think we can have a more efficient grammar instead).
    • Grammar is simplified and optimized
  • Language.EO.Phi.Syntax.* modules are generated by BNFC (but for now included in the repository) and contain abstract syntax definitions, lexer, parser, and pretty-printer.
  • Language.EO.Phi provides the default entry point (defaultMain), and a dummy implementation of the normalizer (normalize), as well as some other utilities
  • test/Language/EO/PhiSpec.hs contains a small test for the normalizer (which currently fails because normalizer is not yet implemented).
  • app/Main.hs is the entry point for the executable (just uses defaultMain)
  • package.yaml is a Haskell package file, describing package contents, dependencies, et.
  • eo-phi-normalizer.cabal — is Cabal package file, and it is generated by Stack (which uses hpack for this) from package.yaml
  • Setup.hs contains customization for the build process. Specifically, we use it to automatically call BNFC to generate Language.EO.Phi.Syntax.* modules from the grammar file.
• stack.yaml specifies a snapshot of all Haskell packages that may be used in dependencies of Haskell packages in this project (we have only one package now)
• hie.yaml specifies settings for the Haskell Language Server
• Basic README with build/test/usage information.
• GitHub Actions workflows
  • GHC build, test, and haddock (source code documentation, published to GitHub Pages)

---

PR-Codex overview

This PR focuses on adding a normalizer for 𝜑-calculus expressions.

Detailed summary

• Added eo-phi-normalizer project
• Added normalize-phi executable
• Added normalization rules for 𝜑-calculus expressions
• Added tests for normalization and prettification
• Updated README with usage instructions

The following files were skipped due to too many changes: README.md, eo-phi-normalizer/package.yaml, eo-phi-normalizer/grammar/EO/Phi/Syntax.old.cf, eo-phi-normalizer/src/Language/EO/Phi/Syntax/Abs.hs, eo-phi-normalizer/src/Language/EO/Phi/Normalize.hs, eo-phi-normalizer/src/Language/EO/Phi/Syntax/Doc.txt, eo-phi-normalizer/eo-phi-normalizer.cabal, eo-phi-normalizer/src/Language/EO/Phi.hs, eo-phi-normalizer/src/Language/EO/Phi/Syntax/Par.y, eo-phi-normalizer/src/Language/EO/Phi/Syntax/Lex.x, eo-phi-normalizer/src/Language/EO/Phi/Syntax/Print.hs

✨ Ask PR-Codex anything about this PR by commenting with /codex {your question}

[yegor256]

@fizruk GitHub action is missing

[deemp]

LGTM 👍