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

Documentation: https://reasonml.org/docs/reason-compiler/latest/new-bucklescript-syntax

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

You don't need this repo to use the new 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/bucklescript/syntax.git cd syntax npm install make # or: make -j9 for faster build

This will produce the final binary lib/napkinscript.exe. "NapkinScript" is the placeholder name for the syntax. We'll change this later to avoid confusion.

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

Debug a file:

# write code in test.js ./lib/napkinscript.exe -print ns test.js # test printer ./lib/napkinscript.exe -print ast test.js # print ast ./lib/napkinscript.exe -print ml test.js # show ocaml code ./lib/napkinscript.exe -print ns -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/napkinscript.exe -parse reasonBinary -print ns > myFile.res node_modules/.bin/bsrefmt --print=binary --interface=true myFile.rei | your/path/to/napkinscript.exe -parse reasonBinary -print ns -interface > myFile.resi mv myFile.re myFile.re.backup # random backup name. Could be anything

module Parser = NapkinscriptCore.Parser module Diagnostics = NapkinscriptCore.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 = NapkinscriptParser.parseImplementation p let signature = NapkinscriptParser.parseInterface p let () = match p.Parser.diagnostics with | [] -> () (* no problems *) | diagnostics -> (* parser contains problems *) prerr_string ( Diagnostics.stringOfReport ~style:Diagnostics.Pretty diagnostics src )