CL/Scheme DSELs with non-lisp syntax

Question

I have been curious lately about DSLs, specifically, how to implement them in Lisp, since it looks like a piece of cake compare to the alternatives.

Looking for information I cannot find any evidence of a non-lisp DSEL in Lisp in internet.

So my question is:

• Is it possible to implement a DSL with non-lisp syntax in lisp with the use of macros?

• How is this achieved?

• Can the reader of lisp be replaced by a custom reader that translates code to lisp structure?

  • If the former is true: is this a common way to implement "non-lispy" DSELs?

Answer 1

Short version: Racket does this.

In more detail: Racket, a descendant of Scheme, has a really well-thought-out story here. A Racket module/file can begin with a language declaration, e.g.

#lang algol60

... and then the rest of the file can be written in the given language. (Yes, algol60 is built in.)

In order to develop your own language, you need to write a package that is a language specification, that shows how to expand the syntax of this language into the syntax of the underlying language (in this case, Racket). Anyone can write such packages, and then distribute them to allow others to write programs in this language. There are examples of such language specifications included with Racket, e.g. the algol 60 example mentioned earlier.

I think this is exactly what you're asking for?

ObDisclaimer: Yes, I am a Racket developer.

Answer 2

How do you implement the surface language of a programming language? You write a parser or use a parser generator. You can do that in Lisp, too.

There are many examples of general purpose and domain specific languages written in Lisp - not using s-expression syntax.

Historically the first ML (an extension language for a theorem prover) was written in Lisp. Macsyma (a language for computer algebra) is written in Lisp. In many cases there is some kind of 'end user', for which a non-s-expression language needs to be written/supported. Sometimes there are languages which exist and need to be supported.

Using macros and read macros you can implement some languages or extend the Lisp language. For example it is easy to add JSON syntax to Lisp using a read macro. Also some kind of infix syntax. XML (example: XMLisp).