fisp's Introduction

fisp

A lisp interpreter implemented in F#.

This loosely follows the tutorial set out in Build Your Own Lisp

Goals of the project:

Create my second language interpreter
Learn Lisp

Notes

In the notes folder, I plan on writing my thoughts about this project periodically. They're categorized by date, so feel free to take a look if you're curious what is going on with this project lately.

Language Spec

Here are the things that I this version of Lisp to do:

Numbers

Can perform basic arithmetic:

fisp> + 1 2
3
fisp> * 1 2
2
fisp> / 2 1
2
fisp> - 1 2
- 1

But arithmetic is limited to 2 expressions

fisp> + 1 2 3
Error: + operator requires 2 expressions, 3 given

Divide by zero is not allowed:

fisp> / 10 0
Error: Cannot divide by zero

Boolean Logic

True and false are simple values:

fisp> #t
#t
fisp> #f
#f

Several boolean operators exist:

fisp> > 1 0
#t
fisp> > 0 1
#f

Strings

String literals are supported:

fisp> "Hello world"
"Hello world"

Todo

See what error message this expression gives and why that is: (+ (5 10) (+ 15 20))
Work on supporting escaped strings (see LexerTests.fs for a unit test on the subject)
Investigate what Lisp/Racket does when combining expressions of different types. Should these give parser errors:
- ((+ 1 "hello world"))
- ((+ ()))
How does Lisp/Racket do string concatenation. Through a basic operator (+) or some defined method
See what is breaking unicode support for strings, is it REPL or something internal to language.

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