go-lisp.go
A simple Lisp interpreter developed in Go.
Go is a perfect fit for building a Lisp interpreter, since it's portable, garbage collected and fast. The result is a one file distribution, which makes it easy to deploy. The garbage collection unloads that work from the interpreter, using the Go already tuned GC.
Inspired by: [http://norvig.com/lispy.html]
Setup
Install Go
Make sure your GOPATH is setup correctly, something like
$ export GOPATH=$HOME/go
$ mkdir -p $GOPATH
Clone the repo
$ go get github.com/janne/go-lisp
Run the tests
$ go test github.com/janne/go-lisp/lisp
Run the example
$ go-lisp -file $HOME/go/src/github.com/janne/go-lisp/example.lsp
Run it interactively
$ go-lisp -i
Syntax
(quote exp)
Return the exp literally; do not evaluate it.
(quote (a b c))
Returns:
(a b c)
(if test conseq alt)
Evaluate test; if true, evaluate and return conseq; otherwise evaluate and return alt.
(if (< 10 20) (+ 1 1) (+ 3 3))
Returns:
2
(set! var exp)
Evaluate exp and assign that value to var, which must have been previously defined (with a define or as a parameter to an enclosing procedure).
(set! x2 (* x x))
(define var exp)
Define a new variable and give it the value of evaluating the expression exp.
(define r 3)
(define square (lambda (x) (* x x)))
(lambda (var...) exp)
Create a procedure with parameter(s) named var... and the expression as the body.
(lambda (r) (* 3.141592653 (* r r)))
(begin exp...)
Evaluate each of the expressions in left-to-right order, and return the final value.
(begin (define x 1) (set! x (+ x 1)) (* x 2))
Returns:
4
(proc exp...)
If proc is anything other than one of the symbols if, set!, define, lambda, begin, or quote then it is treated as a procedure. It is evaluated using the same rules defined here. All the expressions are evaluated as well, and then the procedure is called with the list of expressions as arguments.
(square 12)
Returns:
144
License
Licensed under MIT license.