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bishabosha/Mesa

Functional Language extending the enriched effect calculus. Linear usage of effects. Implemented with Scala 3.
Source code at GitHub https://github.com/bishabosha/Mesa
bishabosha/Mesa.json
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  "createdAt": "2018-12-17T23:58:24Z",
  "defaultBranch": "master",
  "description": "Functional Language extending the enriched effect calculus. Linear usage of effects. Implemented with Scala 3.",
  "fullName": "bishabosha/Mesa",
  "homepage": "",
  "language": "Scala",
  "name": "Mesa",
  "pushedAt": "2025-08-05T16:56:18Z",
  "stargazersCount": 21,
  "topics": [],
  "updatedAt": "2025-08-05T16:56:19Z",
  "url": "https://github.com/bishabosha/Mesa"
}

Mesa

Section titled “Mesa”

Current Release

Section titled “Current Release”

0.3.6-SNAPSHOT

About

Section titled “About”

This repository is for implementing a programming language based on the enriched effect calculus by Egger, Ejlers and Simpson (2014).

Changes

Section titled “Changes”
  • Refer to [CHANGELOG.md]!(CHANGELOG.md)

Features

Section titled “Features”

  • Read Eval Print Loop

    • Define Mesa terms and type-check them.
    • Print the meta AST for Mesa terms and source files.
    • Print the derived types of Mesa terms and source files.
    • Print the current environment of terms and types.

  • Linear types that enforce the linear usage of effects.

    • Proof of isomorphisms in Proposition 4.1. of Egger, Ejlers and Simpson (2014) can be found in [mesa/Isomorphisms.hs]!(mesa/Isomorphisms.hs).

  • Haskell-like syntax

    • Source files use .hs suffix at present to benefit from syntax highlighting.
    • Refer to [mesa/src/main/antlr4/Mesa.g4]!(mesa/src/main/antlr4/Mesa.g4) for a context free grammar.

Author

Section titled “Author”
  • James Thompson, BSc. University of Bath.

Usage

Section titled “Usage”
  • Load sbt with sbt
  • To run tests, in the sbt CLI use test.
  • To launch the EEC REPL, in the sbt CLI use run -e.

REPL

Section titled “REPL”
  • :help to get a list of commands available.
  • :tf to type check a file in the current directory, e.g. mesa/Isomorphisms.hs; adding any definitions to the environment.
  • :ctx to print the current environment after defining terms.
  • :reset to clear all definitions in the environment.
  • :def to define a new top level definition.
  • :t to type an expression.
  • :ast to print the AST of an expression.
  • :astt to print the AST of a top level definition.
  • :astf to print the AST of a source file in the current directory.
  • :cd to change the working directory
  • :pwd to print the working directory
  • :q to quit the REPL.

References

Section titled “References”
  • Egger, J., Ejlers, R. and Simpson, A., 2014. The enriched effect calculus: syntax and semantics. Journal of Logic and Computation, 24(3), pp.615-654.