Reduced-Lisp in Scala Processor, Risp, is a simple language/internal DSL written in Scala that aims to be a simplified but type-safe Lisp.

I have absolutely no need for something like this, but maybe some brighter minds on the internet can have some fun with it.

To scratch an itch, mostly. Also, recently found out that TailRec implements map and flatMap, so I wanted to write a stack-safe interpreter (see risp.Eval).

There are a bunch of examples everywhere on how to implement traditional Lisps in Scala on the internet, and they are usually either dynamically typed, compile from non-Scala to Scala, or a combination of both. Risp is different in that it is both implemented and written in Scala, and type-safe.

import risp._, dsl._, IntOps._

// declaring a function
case object ToInt extends BaseFunc[String, Int](_.toInt, (acc, next) => acc * 10 + next.toInt)

val expr = |(Add, 1, 2, |(ToInt, "1", "2")) // => (Add 1 2 (ToInt 1 2))
val r = Eval(expr)
assert(r == Some(15))

For version, see Maven badge.

libraryDependencies += "com.beachape" %% "risp" % version