epfl-lara/scallion

LL(1) parser combinators in Scala

Overview

Scallion is a library for writing parsers and pretty printers for LL(1) languages in Scala.

Documentation

A comprehensive Scaladoc API is available online.

Parsing Algorithm

Scallion uses a novel parsing algorithm that we have described in the PLDI'20 paper: Zippy LL(1) Parsing with Derivatives. The algorithm has been formally proven correct in Coq.

Examples

• JSON: This example showcases how to build a basic JSON parser using Scallion.
• Lambda Calculus: This example shows how to get a pretty printer almost for free alongside your parser.
• Calculator: This example shows how to use the operators combinator to easily handle operators with various associativities and priorities.
• Roman Numerals: This example presents a simple parser and pretty printer for roman numerals.

scallion's Issues

Remove bintray

Make Scallion either a non-dependency or a source dependency.
Consequently, do not rely on defunct bintray.

@redelmann : how we produce token stream should not matter for Scallion, or?

Benchmarks do not compile

The project has been upgraded to Scala 3 but the benchmarks are still in Scala 2.12 (in particular, parseback-core and parseback-cats dependencies are available in Scala 2.12 at the latest; it is possible to upgrade other dependencies to Scala 2.13 or Scala 3) which is incompatible.

Add support for operators

Basically port my port for Fastparse of Megaparsec's operators :p

Source dependency on silex times out

My attempt to start sbt times out while trying to fetch silex source depenency:

[info] loading settings for project scallion from build.sbt ...
Cloning into '..../.sbt/1.0/staging/..../silex'...

(waits for long and gives up)

Any idea? My sbt defaults to 1.7.2

Set-up larabot

I have already added an entry for Scallion in the larabot config, now it should only be a matter of setting up the proper webhook for Scallion, using the same secret as your treenet project.