X-Git-Url: http://git.lukelau.me/?p=scheme.git;a=blobdiff_plain;f=typecheck.scm;h=d180e44e92e755f1e4fbb4172f3535e70f8ebb24;hp=4cc93495fb9dd6bc90b03b9b06271e316c65a8bb;hb=8e106ca13666680051f91ab3f49ce2bd7e19ead7;hpb=a64f7097fa246c19a4c69d0aad65e60378273887

diff --git a/typecheck.scm b/typecheck.scm
index 4cc9349..d180e44 100644
--- a/typecheck.scm
+++ b/typecheck.scm
@@ -37,7 +37,7 @@
 
 					; ('a, ('b, 'a))
 (define (env-lookup env n)
-  (if (null? env) (error #f "empty env")			; it's a type equality
+  (if (null? env) (error #f "empty env" env n)			; it's a type equality
       (if (eq? (caar env) n)
 	  (cdar env)
 	  (env-lookup (cdr env) n))))
@@ -91,11 +91,9 @@
     (else (error #f "Couldn't find type for builtin" x))))
 
 (define (check-let env x)
-  					; takes in the current environment and a scc
-					; returns new environment with scc's types added in
-  (let* ([components (reverse (sccs (graph (let-bindings x))))]
-	 [process-component
-	  (lambda (acc comps)
+
+  ; acc is a pair of (env . annotated bindings)
+  (define (process-component acc comps)
     (let*
 					; create a new env with tvars for each component
 					; e.g. scc of (x y)
@@ -104,7 +102,7 @@
 	  (fold-left
 	   (lambda (acc c)
 	     (env-insert acc c (fresh-tvar)))
-		   acc comps)]
+	   (car acc) comps)]
 					; typecheck each component
 	 [type-results
 	  (map
@@ -130,24 +128,82 @@
 		 (if (memv (car x) comps)
 		     (cons (car x) (substitute cs (cdr x)))
 		     x))
-		       scc-env)])
-	      new-env))]
-	 [new-env (fold-left process-component env components)])
-    (check new-env (last (let-body x)))))
+	       scc-env)]
+
+	 [annotated-bindings (append (cdr acc) ; the previous annotated bindings
+				     (map list
+					  comps
+					  (map caddr type-results)))])
+      (cons new-env annotated-bindings)))
+  					; takes in the current environment and a scc
+					; returns new environment with scc's types added in
+  (let* ([components (reverse (sccs (graph (let-bindings x))))]
+	 [results (fold-left process-component (cons env '()) components)]
+	 [new-env (car results)]
+	 [annotated-bindings (cdr results)]
+
+	 [body-results (map (lambda (body) (check new-env body)) (let-body x))]
+	 [let-type (cadr (last body-results))]
+	 [cs (fold-left (lambda (acc cs) (constraint-merge acc cs)) '() (map car body-results))]
+
+	 [annotated `((let ,annotated-bindings ,@(map caddr body-results)) : ,let-type)])
+    (list cs let-type annotated)))
+
+(define (check-app env x)
+  (if (eqv? (car x) (cadr x))
+					; recursive function (f f)
+					; TODO: what about ((f a) f)????
+      (let* ([func-type (env-lookup env (car x))]
+	     [return-type (fresh-tvar)]
+	     [other-func-type `(abs ,func-type ,return-type)]
+	     [cs (~ func-type other-func-type)]
+	     [resolved-return-type (substitute cs return-type)]
+
+	     [annotated `(((,(car x) : ,func-type)
+			   (,(cadr x) : ,func-type)) : ,resolved-return-type)])
+	(list cs resolved-return-type annotated)))
+
+					; regular function
+  (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)]
+	 
+					; f ~ a -> t0
+	 [func-c (~
+		  (substitute (car arg-type-res) func-type)
+		  `(abs ,arg-type ,(fresh-tvar)))]
+	 [cs (constraint-merge
+	      (constraint-merge func-c (car arg-type-res))
+	      (car func-type-res))]
+	 
+	 [resolved-func-type (substitute cs func-type)]
+	 [resolved-return-type (caddr resolved-func-type)]
+
+	 [annotated `((,(caddr func-type-res)
+		       ,(caddr arg-type-res)) : ,resolved-return-type)])
+
+    (if (abs? resolved-func-type)
+	(let ((return-type (substitute cs (caddr resolved-func-type))))
+	  (list cs return-type annotated))
+	(error #f "not a function"))))
 
+; returns a list (constraints type annotated)
 (define (check env x)
-  (display "check: ")
-  (display x)
-  (display "\n\t")
-  (display env)
-  (newline)
+  (define (make-result cs type)
+    (list cs type `(,x : ,type)))
+  ;; (display "check: ")
+  ;; (display x)
+  ;; (display "\n\t")
+  ;; (display env)
+  ;; (newline)
   (let
       ((res
 	(case (ast-type x)
-	  ('int-literal (list '() 'Int))
-	  ('bool-literal (list '() 'Bool))
-	  ('string-literal (list '() 'String))
-	  ('builtin (list '() (builtin-type x)))
+	  ('int-literal (make-result '() 'Int))
+	  ('bool-literal (make-result '() 'Bool))
+	  ('string-literal (make-result '() 'String))
+	  ('builtin (make-result '() (builtin-type x)))
 
 	  ('if
 	   (let* ((cond-type-res (check env (cadr x)))
@@ -160,97 +216,107 @@
 		       (constraint-merge (~ (cadr cond-type-res) 'Bool)
 					 (constraint-merge (car else-type-res)
 							   then-eq-else-cs))))
-		  (return-type (substitute cs (cadr then-type-res))))
-	     (list cs return-type)))
+		  (return-type (substitute cs (cadr then-type-res)))	      
+		  [annotated `((if ,(caddr cond-type-res)
+				   ,(caddr then-type-res)
+				   ,(caddr else-type-res)) : ,return-type)])
+	     (list cs return-type annotated)))
 	  
-	  ('var (list '() (env-lookup env x)))
+	  ('var (make-result '() (env-lookup env x)))
 	  ('let (check-let env x))
 
 	  
 	  ('lambda
-	      (let* [(new-env (env-insert env (lambda-arg x) (fresh-tvar)))
-
-		     (body-type-res (check new-env (lambda-body x)))
-		     (cs (car body-type-res))
-		     (subd-env (substitute-env (car body-type-res) new-env))
-		     (arg-type (env-lookup subd-env (lambda-arg x)))
-		     (resolved-arg-type (substitute cs arg-type))]
-		;; (display "lambda:\n\t")
-		;; (display prog)
-		;; (display "\n\t")
-		;; (display cs)
-		;; (display "\n\t")
-		;; (display (format "subd-env: ~a\n" subd-env))
-		;; (display resolved-arg-type)
-		;; (newline)
-		(list (car body-type-res)
-		      (list 'abs
-			    resolved-arg-type
-			    (cadr body-type-res)))))
+	      (let* ([new-env (env-insert env (lambda-arg x) (fresh-tvar))]
 
-	  ('app ; (f a)
-	   (if (eqv? (car x) (cadr x))
-					; recursive function (f f)
-	       (let* [(func-type (env-lookup env (car x)))
-		      (return-type (fresh-tvar))
-		      (other-func-type `(abs ,func-type ,return-type))
-		      (cs (~ func-type other-func-type))
-		      (resolved-return-type (substitute cs return-type))]
-		 (list cs resolved-return-type)))
+		     [body-type-res (check new-env (lambda-body x))]
+		     [cs (car body-type-res)]
+		     [subd-env (substitute-env (car body-type-res) new-env)]
+		     [arg-type (env-lookup subd-env (lambda-arg x))]
+		     [resolved-arg-type (substitute cs arg-type)]
 
-					; regular function
-	       (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))
+		     [lambda-type `(abs ,resolved-arg-type ,(cadr body-type-res))]
 
-					; f ~ a -> t0
-		      (func-c (~
-			       (substitute (car arg-type-res) func-type)
-			       `(abs ,arg-type ,(fresh-tvar))))
-		      (cs (constraint-merge
-			   (constraint-merge 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)
-		     (let ((return-type (substitute cs (caddr resolved-func-type))))
-		       (list cs return-type))
-		     (error #f "not a function")))))))
-    (display "result of ")
-    (display x)
-    (display ":\n\t")
-    (display (pretty-type (cadr res)))
-    (display "\n\t[")
-    (display (pretty-constraints (car res)))
-    (display "]\n")
+		     [annotated `((lambda (,(lambda-arg x)) ,(caddr body-type-res)) : ,lambda-type)])
+		
+		(list (car body-type-res) ; constraints
+		      lambda-type  ; type
+		      annotated)))
+
+	  
+	  ('app (check-app env x)))))
+    ;; (display "result of ")
+    ;; (display x)
+    ;; (display ":\n\t")
+    ;; (display (pretty-type (cadr res)))
+    ;; (display "\n\t[")
+    ;; (display (pretty-constraints (car res)))
+    ;; (display "]\n")
     res))
 
+(define (init-adts-env prog)
+  (flat-map data-tors-type-env (program-data-layouts prog)))
+
 					; we typecheck the lambda calculus only (only single arg lambdas)
 (define (typecheck prog)
-  (define (constructor-type t ctr)
-    (fold-left (lambda (acc x) `(abs ,x ,acc)) t (cdr ctr)))
-  (define (constructors data-def)
-    (let ([type-name (cadr data-def)]
-	  [ctrs (cddr data-def)])
-    (fold-left (lambda (acc ctr)
-		 (cons (cons (car ctr) (constructor-type type-name ctr))
-		       acc))
-	       '()
-	       ctrs)))
-  (let ([init-env (flat-map constructors (program-datas prog))])
-    (display init-env)
-    (cadr (check init-env (normalize (program-body prog))))))
+  (let ([expanded (expand-pattern-matches prog)])
+    (cadr (check (init-adts-env expanded) (normalize (program-body expanded))))))
+
+
+					; before passing annotated types onto codegen
+					; we need to restore the pre-normalization structure
+					; (this is important for function arity etc)
+(define (denormalize orig normed)
+
+  (define (collapse-lambdas n x)
+    (case n
+      [0 x]
+      [else
+       (let* ([inner-lambda (lambda-body (ann-expr x))]
+	      [arg (lambda-arg (ann-expr x))]
+	      [inner-collapsed (ann-expr (collapse-lambdas (- n 1) inner-lambda))])
+	 `((lambda ,(cons arg (lambda-args inner-collapsed))
+	     ,(lambda-body inner-collapsed)) : ,(ann-type x)))]))
+
+  (define (collapse-apps n x)
+    (case n
+      [-1 (error #f "nullary functions not handled yet")]
+      [0 x]
+      [else
+       (let* ([inner-app (car (ann-expr x))]
+	      [inner-collapsed (collapse-apps (- n 1) inner-app)])
+	 `(,(append (ann-expr inner-collapsed) (cdr (ann-expr x))) : ,(ann-type x)))]))
+
+  (case (ast-type orig)
+    ['lambda
+	(let ([collapsed (collapse-lambdas (- (length (lambda-args orig)) 1) normed)])
+	  `((lambda ,(lambda-args (ann-expr collapsed))
+	      ,(denormalize (lambda-body orig)
+			    (lambda-body (ann-expr collapsed)))) : ,(ann-type collapsed)))]
+    ['app
+     (let ([collapsed (collapse-apps (- (length orig) 2) normed)])
+       `(,(map (lambda (o n) (denormalize o n)) orig (ann-expr collapsed))
+	 : ,(ann-type collapsed)))]
+    ['let
+	`((let ,(map (lambda (o n) (list (car o) (denormalize (cadr o) (cadr n))))
+		     (let-bindings orig)
+		     (let-bindings (ann-expr normed)))
+	    ,@(map (lambda (o n) (denormalize o n))
+		   (let-body orig)
+		   (let-body (ann-expr normed)))) : ,(ann-type normed))]
+    ['if `((if ,@(map denormalize (cdr orig) (cdr (ann-expr normed))))
+	   : (ann-type normed))]
+    [else normed]))
+
+(define ann-expr car)
+(define ann-type caddr)
+
+					; prerequisites: expand-pattern-matches
+(define (annotate-types prog)
+  (denormalize
+   (program-body prog)
+   (caddr (check (init-adts-env prog) (normalize (program-body prog))))))
+
   
 					; returns a list of constraints
 (define (~ a b)
@@ -338,108 +404,4 @@
 
 					; input: a list of binds ((x . y) (y . 3))
 					; returns: pair of verts, edges ((x y) . (x . y))
-(define (graph bs)
-  (define (go bs orig-bs)
-    (define (find-refs prog)
-      (ast-collect
-       (lambda (x)
-	 (case (ast-type x)
-					; only count a reference if its a binding
-	   ['var (if (assoc x orig-bs) (list x) '())]
-	   [else '()]))
-       prog))
-    (if (null? bs)
-	'(() . ())
-	(let* [(bind (car bs))
-
-	       (vert (car bind))
-	       (refs (find-refs (cdr bind)))
-	       (edges (map (lambda (x) (cons vert x))
-			   refs))
-
-	       (rest (if (null? (cdr bs))
-			 (cons '() '())
-			 (go (cdr bs) orig-bs)))
-	       (total-verts (cons vert (car rest)))
-	       (total-edges (append edges (cdr rest)))]
-	  (cons total-verts total-edges))))
-  (go bs bs))
-
-(define (successors graph v)
-  (define (go v E)
-    (if (null? E)
-	'()
-	(if (eqv? v (caar E))
-	    (cons (cdar E) (go v (cdr E)))
-	    (go v (cdr E)))))
-  (go v (cdr graph)))
-
-					; takes in a graph (pair of vertices, edges)
-					; returns a list of strongly connected components
-
-					; ((x y w) . ((x . y) (x . w) (w . x))
-
-					; =>
-					; .->x->y
-					; |  |
-					; |  v
-					; .--w
-
-					; ((x w) (y))
-
-					; this uses tarjan's algorithm, to get reverse
-					; topological sorting for free
-(define (sccs graph)
-  
-  (let* ([indices (make-hash-table)]
-	 [lowlinks (make-hash-table)]
-	 [on-stack (make-hash-table)]
-	 [current 0]
-	 [stack '()]
-	 [result '()])
-
-    (define (index v)
-      (get-hash-table indices v #f))
-    (define (lowlink v)
-      (get-hash-table lowlinks v #f))
-
-    (letrec
-	([strong-connect
-	  (lambda (v)
-	    (begin
-	      (put-hash-table! indices v current)
-	      (put-hash-table! lowlinks v current)
-	      (set! current (+ current 1))
-	      (push! stack v)
-	      (put-hash-table! on-stack v #t)
-
-	      (for-each
-	       (lambda (w)
-		 (if (not (hashtable-contains? indices w))
-					; successor w has not been visited, recurse
-		     (begin
-		       (strong-connect w)
-		       (put-hash-table! lowlinks
-					v
-					(min (lowlink v) (lowlink w))))
-					; successor w has been visited
-		     (when (get-hash-table on-stack w #f)
-		       (put-hash-table! lowlinks v (min (lowlink v) (index w))))))
-	       (successors graph v))
-
-	      (when (= (index v) (lowlink v))
-		(let ([scc
-		       (let new-scc ()
-			 (let ([w (pop! stack)])
-			   (put-hash-table! on-stack w #f)
-			   (if (eqv? w v)
-			       (list w)
-			       (cons w (new-scc)))))])
-		  (set! result (cons scc result))))))])
-      (for-each
-       (lambda (v)
-	 (when (not (hashtable-contains? indices v)) ; v.index == -1
-	   (strong-connect v)))
-       (car graph)))
-    result))