let-go

Greetings loafers! (λ-gophers haha, get it?)

This is a bytecode compiler and VM for a language closely resembling Clojure, a Clojure dialect, if you will.

Here are some nebulous goals in no particular order:

• Quality entertainment,
• Making it legal to write Clojure at your Go dayjob,
• Implement as much of Clojure as possible - including persistent data types and true concurrency,
• Provide comfy two-way interop for arbitrary functions and types,
• AOT (let-go -> standalone binary) would be nice eventually,
• Strech goal: let-go bytecode -> Go translation.

Here are the non goals:

• Stellar performance (cough cough, it seems to be faster than Joker),
• Being a drop-in replacement for clojure/clojure at any point,
• Being a linter/formatter/tooling for Clojure in general.

Current status

It can eval a Clojure-like lisp. It's semi-good for solving Advent of Code problems but not for anything more serious yet.

There are some goodies:

• Macros with syntax quote,
• Reader conditionals,
• Destructuring,
• Multi-arity functions,
• Atoms, channels & go-blocks a'la core.async,
• Regular expressions (the Go flavor),
• Simple json, http and os namespaces,
• Many functions ported from clojure.core,
• REPL with syntax-highlighting and completions,
• Simple nREPL server that seems to work with BetterThanTomorrow/calva,

I'm currently contemplating:

• Dynamic variables,
• Exceptions & more comprehensive runtime errors,
• Numeric tower i.e. floats, bignums and other exotic number species,
• Optimized persistent data-structures and laziness,
• Records and protocols,
• A real test suite would be nice,

Examples

See:

• My AoC 2022 solutions for an idea of how let-go looks like,
• Examples for small programs I wrote on a whim,
• Tests for some random "tests".

Try online

Check out this bare-bones online REPL. It runs a WASM build of let-go in your browser!

Prerequisites and installation

Building or running let-go from source requires Go 1.19.

go install github.com/nooga/let-go@latest

Try it out:

let-go

Running from source

The best way to play with let-go right now is to clone this repo and run the REPL like this:

go run . 

To run an expression:

go run . -e '(+ 1 1)'

To run a file:

go run . test/hello.lg

Use the -r flag to run the REPL after the interpreter has finished with files and -e:

go run . -r test/simple.lg                # will run simple.lg first, then open up a REPL
go run . -r -e '(* fun 2)' test/simple.lg # will run simple.lg first, then (* fun 2) and REPL 

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