--- /dev/null
+(load "typecheck.scm")
+
+(define (emit . s)
+ (begin
+ (apply printf s)
+ (display "\n")))
+
+(define (compile-add xs)
+ (define (go ys)
+ (if (null? ys)
+ (emit "movq %rbx, %rax")
+ (begin
+ (emit "addq $~a, %rbx" (car ys))
+ (go (cdr ys)))))
+ (begin
+ (emit "movq $0, %rbx")
+ (go xs)))
+
+(define (compile-expr e)
+ (if (and (list? e) (eq? (car e) '+))
+ (compile-add (cdr e))
+ (emit "movq $~a, %rax" e)))
+
+(define (compile-program program)
+ (emit ".text")
+ (emit ".p2align 4,,15")
+ (emit ".globl _scheme_entry")
+ (emit "_scheme_entry:")
+
+ ; handle incoming call from C
+ (emit "push %rbp")
+ (emit "push %rbx")
+ (for-each (lambda (i)
+ (emit (string-append
+ "push %r"
+ (number->string i))))
+ '(12 13 14 15))
+
+ ; our code goes here
+ (compile-expr program)
+
+ ; restore preserved registers
+ (for-each (lambda (i)
+ (emit (string-append
+ "pop %r"
+ (number->string i))))
+ '(15 14 13 12))
+ (emit "pop %rbx")
+ (emit "pop %rbp")
+
+ (emit "ret"))
+
+(define (compile-to-binary program)
+ (when (not (eq? (typecheck program) 'int)) (error #f "not an int"))
+ (let ([tmp-path "/tmp/a.s"])
+ (when (file-exists? tmp-path) (delete-file tmp-path))
+ (with-output-to-file tmp-path
+ (lambda () (compile-program program)))
+ (system "clang -fomit-frame-pointer /tmp/a.s rts.c")))
-(define (is-app? x)
- (and (list? x) (not (eq? (car x) 'lambda))))
+(define (app? x)
+ (and (list? x) (>= (length x) 2) (not (eq? (car x) 'lambda))))
-
-(define (is-lambda? x)
+(define (lambda? x)
(and (list? x) (eq? (car x) 'lambda)))
-(define lambda-arg cadr)
+(define lambda-arg caadr)
(define lambda-body caddr)
; ('a, ('b, 'a))
(string->symbol
(string-append "t" (number->string (- cur-tvar 1))))))
-(define (typecheck env x)
- (display "typechecking:\n\t")
- (display x)
- (display "\t")
- (display env)
- (display "\n")
+
+(define (normalize prog) ; (+ a b) -> ((+ a) b)
+ (cond
+ ((lambda? prog) '(lambda (lambda-arg prog) (normalize (lambda-body prog))))
+ ((app? prog)
+ (if (null? (cddr prog))
+ (cons (normalize (car prog)) (normalize (cdr prog))) ; (f a)
+ (normalize (cons (cons (car prog) (list (cadr prog))) (cddr prog))))) ; (f a b)
+ (else prog)))
+
+
+(define (typecheck prog)
+ (define (check env x)
(let
((res
(cond
((integer? x) (list '() 'int))
((boolean? x) (list '() 'bool))
((eq? x 'inc) (list '() '(abs int int)))
+ ((eq? x '+) (list '() '(abs int (abs int int))))
((symbol? x) (list '() (env-lookup env x)))
- ((is-lambda? x)
+ ((lambda? x)
(let* ((new-env (cons (cons (lambda-arg x) (fresh-tvar)) env))
- (body-type-res (typecheck new-env (lambda-body x)))
- (subd-env (substitute (car body-type-res) new-env)))
- (display "lambda: ")
- (display body-type-res)
- (display "\n")
+ (body-type-res (check new-env (lambda-body x)))
+ (subd-env (substitute-env (car body-type-res) new-env)))
+ ;; (display "lambda: ")
+ ;; (display body-type-res)
+ ;; (display "\n")
+ ;; (display subd-env)
+ ;; (display "\n")
(list (car body-type-res)
(list 'abs
(env-lookup subd-env (lambda-arg x))
(cadr body-type-res)))))
- ((is-app? x) ; (f a)
- (let* ((arg-type-res (typecheck env (cadr x)))
- ; typecheck f with the knowledge that f : a -> x
- (func-type-res (typecheck env (car x)))
+ ((app? x) ; (f a)
+ (let* ((arg-type-res (check env (cadr x)))
+ (arg-type (cadr arg-type-res))
+ (func-type-res (check env (car x)))
(func-type (cadr func-type-res))
- (c (unify func-type
+
+ ; f ~ a -> t0
+ (func-c (unify func-type
(list 'abs
- (cadr arg-type-res)
+ arg-type
(fresh-tvar))))
- (new-env (substitute c env))
- (resolved-func-type (env-lookup new-env (car x))))
- (display "is-app:\n")
- (display c)
- (display "\n")
- (display new-env)
- (display "\n")
- (display resolved-func-type)
- (display "\n")
- (display arg-type-res)
- (display "\n")
+ (cs (append func-c (car arg-type-res) (car func-type-res)))
+
+ (resolved-func-type (substitute cs func-type))
+ (resolved-return-type (caddr resolved-func-type)))
+ ;; (display "app:\n")
+ ;; (display cs)
+ ;; (display "\n")
+ ;; (display func-type)
+ ;; (display "\n")
+ ;; (display resolved-func-type)
+ ;; (display "\n")
+ ;; (display arg-type-res)
+ ;; (display "\n")
(if (abs? resolved-func-type)
- (list (append c
- (unify (cadr arg-type-res)
- (cadr resolved-func-type)))
- (caddr resolved-func-type))
+ (let ((return-type (substitute cs (caddr resolved-func-type))))
+ (list cs return-type))
(error #f "wah")))))))
- (display "result of ")
- (display x)
- (display ":\n\t")
- (display (cadr res))
- (display "[")
- (display (car res))
- (display "]\n")
+ ;; (display "result of ")
+ ;; (display x)
+ ;; (display ":\n\t")
+ ;; (display (cadr res))
+ ;; (display "[")
+ ;; (display (car res))
+ ;; (display "]\n")
res))
+ (cadr (check '() (normalize prog))))
(define (abs? t)
; returns a list of pairs of constraints
(define (unify a b)
(cond ((eq? a b) '())
- ((or (tvar? a) (tvar? b)) (list (cons a b)))
+ ((or (tvar? a) (tvar? b)) (~ a b))
((and (abs? a) (abs? b))
- (append (unify (cadr a) (cadr b))
+ (consolidate (unify (cadr a) (cadr b))
(unify (caddr a) (caddr b))))
(else (error #f "could not unify"))))
- ; takes a list of constraints and a type environment, and makes it work
-(define (substitute c env)
- (let ((go (lambda (x) (let ((tv (cdr x))
- (n (car x)))
- ;; (display tv)
- ;; (display "\n")
- ;; (display n)
- (cons n (fold-left
- (lambda (a y)
- ;; (display y)
- ;; (display ":")
- ;; (display a)
- (cond ((eq? a (car y)) (cdr y))
- ((eq? a (cdr y)) (car y))
- (else a)))
- tv c))))))
- (map go env)))
+
+ ; TODO: what's the most appropriate substitution?
+ ; should all constraints just be limited to a pair?
+(define (substitute cs t)
+ (define (blah c)
+ (if (null? (cdr c))
+ (car c)
+ (if (not (tvar? (car c)))
+ (car c)
+ (blah (cdr c)))))
+ (fold-left
+ (lambda (t c)
+ (if (member t c)
+ (blah c)
+ t))
+ t cs))
+
+(define (substitute-env cs env)
+ (map (lambda (x) (cons (car x) (substitute cs (cdr x)))) env))
+
+(define (~ a b)
+ (list (list a b)))
+
+(define (consolidate x y)
+ (define (merge a b)
+ (cond ((null? a) b)
+ ((null? b) a)
+ (else (if (member (car b) a)
+ (merge a (cdr b))
+ (cons (car b) (merge a (cdr b)))))))
+ (define (overlap? a b)
+ (if (or (null? a) (null? b))
+ #f
+ (if (fold-left (lambda (acc v)
+ (or acc (eq? v (car a))))
+ #f b)
+ #t
+ (overlap? (cdr a) b))))
+
+ (cond ((null? y) x)
+ ((null? x) y)
+ (else (let* ((a (car y))
+ (merged (fold-left
+ (lambda (acc b)
+ (if acc
+ acc
+ (if (overlap? a b)
+ (cons (merge a b) b)
+ #f)))
+ #f x))
+ (removed (if merged
+ (filter (lambda (b) (not (eq? b (cdr merged)))) x)
+ x)))
+ (if merged
+ (consolidate removed (cons (car merged) (cdr y)))
+ (consolidate (cons a x) (cdr y)))))))