Polyglot Language Understanding

Surveys of projects/research that try to understand multiple programming languages in a "unified" way.

To varying degrees, they're valuable "corpuses" of language info.

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Note: light is not necessarily better than heavy!

It refers to how much code is shared between language "back ends". If no code is shared, it's "heavy".

Lightweight Implementations

• ctags (Universal, Exuberant) -- Integrated with vim. Very approximate, text-only analysis of languages.

  • See FAQ on "what happens when it's wrong?"
  • Although it's not clear how much sharing there is

• uchex (Stanford paper, 2016)

  • micro-grammars, parser combinators
  • "belief-style checkers" (not the only supported technique)
  • Haskell Parsec, original implementation was Python

• Concept: Island Grammars

  • An island grammar only precisely defines small portions of the syntax of a language. The rest of the syntax is defined imprecisely, for instance as a list of characters, or a list of tokens.

These two appear fairly approximate?

• Comby (OCaml), Strange Loop Talk, CMU paper
  • parser parser combinators
  • https://comby.dev/en/projects
• sylver - not open source?
  • Sylver is a language-agnostic tool for source code exploration and analysis.
  • *Using the SYLQ query language REPL, you can perform syntax-aware search on your codebase to find

Heavyweight Implementations

• semgrep / coccinelle (OCaml)
  • Semgrep: a static analysis journey (2021) - How an academic project for the Linux kernel evolved into a multilingual security tool
  • INRIA -> Facebook -> r2c
  • facebook/pfff repo (OCaml) style issues and potential bugs.*
• github/semantic -- appears inactive
  • Haskell
• Google Kythe

Polyglot Interfaces

• SCIP - a better code indexing format than LSIF (2022)

  • Sourcegraph code navigation such as “Go to definition” comes in two flavors: search-based and precise. Search-based code navigation is available out-of-the-box. It is fast and always available, but it can occasionally return false-positive and false-negative results. Precise code navigation, on the other hand, requires custom configuration to set up, but the results are compiler-accurate and work across repositories. Both search-based and precise code navigation are useful in their own ways. While search-based is less powerful, it is a quick and convenient solution. Precise is more powerful, but it also requires more upfront investment to configure.
  • scip-typescript: a new TypeScript and JavaScript indexer
    • https://github.com/sourcegraph/scip-typescript
  • https://github.com/sourcegraph/scip-java

• Language Server Protocol

Other Surveys

• Alternative Shells
• Alternative Regex Syntax