7 lines of code, 3 minutes: Implement a programming language from scratch

Exactly. Once could say you can write all of perl in perl by using eval().

Obligatory Sagan quote: “If you want to make an apple pie from scratch, you must first create the universe.”

I'm often annoyed that between language theory and language implementation there is the trouble of lexing and parsing. Both are complex and take a lot of time and know-how (at least for me as they never work right the first time), and it's not until you have those done that you can actually work on language features.

Lisp is handy from it's data-is-code mentality it already has a general-purpose parser built in. It's something that is fairly easy to implement for functional languages which is much harder to implement for OOP languages.

Yes.

If you went to the University of Utah, he probably taught it (http://matt.might.net/#teaching).

It will look suspiciously similar to the Scripting Language Design and Implementation class that I'll be teaching.

This kind of stuff also showed up in my program analysis and advanced compiler classes, too.

One of the class projects was to implement first-class macros, and we used an interpreter that looked a lot like the one from this article:

http://matt.might.net/articles/metacircular-evaluation-and-f...

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Be glad you didn't go to school 20 years ago. I had to build a Lisp-1 REPL in Pascal on an IBM mainframe without a debugger for my programming languages class.

(I also had to walk to class barefoot in the snow uphill both ways)

A lisp with T, NIL, if, and lambda, like "tiny-lisp" here:

http://tfeb.org/lisp/hax.html#CONDUITS

Literally, a package hack with zero implementation :-)

Import defmacro and friends and you have it.

That's a good question, actually.

Lisp macros need knowledge of the structure of the s-expression.

Certainly one can Church encode s-expressions and provide defmacro.

Gensym is trickier. Hygiene might be really challenging.

I might actually try that out.

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McCarthy's original could give you macros, although they would be extremely cumbersome. I've been wanting to implement some sort of macro system in my minimal Lisp impl. http://github.com/fogus/lithp

A challenge: get something comparable to macros out of Forth.