Blog post: https://reasonml.org/blog/bucklescript-8-1-new-syntax

Documentation: https://rescript-lang.org/docs/manual/latest/overview

This repo is the source of truth for the ReScript parser & printer. Issues go here.

You don't need this repo to use the ReScript syntax. This comes with BuckleScript 8.1. This repo is for syntax contributors.

A detailed discussion by Jonathan Blow and Casey Muratori on why you would hand-roll a parser for a production quality programming language Discussion: Making Programming Language Parsers, etc

"One reason why I switched off these parser tools is that the promises didn't really materialize. The amount of work that I had to do change a yacc script from one language to a variant of that language was more than if I hand wrote the code myself. " J. Blow.

Currently for devs only.

Required:

• NodeJS
• Ocaml 4.06.1
• OS: Mac

opam switch create 4.06.1 && eval $(opam env) git clone https://github.com/rescript-lang/syntax.git cd syntax npm install make # or: make -j9 for faster build

This will produce the final binary lib/rescript.exe used for testing

First build is super slow because we're also building our vendored refmt (only used for the conversion tool). Subsequent builds should be <2s. If not, please file an issue (build speed is a priority).

We only build production binary, even in dev mode. No need for a separate dev binary when the build is fast enough. Plus, this encourages proper benchmarking of the (production) binary each diff.

After you make a change:

make

Run the core tests:

make test

Run the extended tests:

make roundtrip-test

Update jest snapshots:

./node_modules/.bin/jest -u

Debug a file:

# write code in test.js ./lib/rescript.exe test.js # test printer ./lib/rescript.exe -print ast test.js # print ast ./lib/rescript.exe -print ml test.js # show ocaml code ./lib/rescript.exe -print res -width 80 test.js # test printer and change default print width

Benchmark:

make bench

src/syntax contains all the source code. Don't change folder structure without notice; BuckleScript uses this repo as a submodule and assumes src/syntax.

In a random project of yours:

node_modules/.bin/bsrefmt --print=binary myFile.re | your/path/to/rescript.exe -parse reasonBinary -print ns > myFile.res node_modules/.bin/bsrefmt --print=binary --interface=true myFile.rei | your/path/to/rescript.exe -parse reasonBinary -print ns -interface > myFile.resi mv myFile.re myFile.re.backup # random backup name. Could be anything

module Parser = ResCore.Parser module Diagnostics = ResCore.Diagnostics let filename = "foo.res" let src = FS.readFile filename let p = (* intended for ocaml compiler *) let mode = Parser.ParseForTypeChecker in (* if you want to target the printer use: let mode = Parser.Default in*) Parser.make ~mode src filename let structure = ResParser.parseImplementation p let signature = ResParser.parseInterface p let () = match p.Parser.diagnostics with | [] -> () (* no problems *) | diagnostics -> (* parser contains problems *) prerr_string ( Diagnostics.stringOfReport ~style:Diagnostics.Pretty diagnostics src )