X-Git-Url: https://git.lukelau.me/?p=scheme.git;a=blobdiff_plain;f=ast.scm;h=b70317a70e6fd3a14aa9fab5c94be57991427f2e;hp=4ca6eb1e1dc57100a344310ea1494ea2139236e0;hb=8e106ca13666680051f91ab3f49ce2bd7e19ead7;hpb=89ef32141732e6d0bbfc7484b465844b62d8d139

diff --git a/ast.scm b/ast.scm
index 4ca6eb1..b70317a 100644
--- a/ast.scm
+++ b/ast.scm
@@ -1,3 +1,5 @@
+(load "utils.scm")
+
 (define (ast-type x)
   (define (builtin? x)
     (case x
@@ -17,6 +19,7 @@
       ('lambda 'lambda)      
       ('closure 'closure) ; only available in codegen
       ('static-string 'static-string) ; only available in codegen
+      ('stack 'stack) ; only available in codegen (tag that value is passed via stack)
       (else 'app)))
    ((builtin? x) 'builtin)
    ((symbol? x) 'var)
@@ -32,6 +35,7 @@
     ('app (map f x))
     ('lambda `(lambda ,(lambda-args x) ,(f (lambda-body x))))
     ('if `(if ,@(map f (cdr x))))
+    ('stack `(stack ,(cadr x) ,(f (caddr x))))
     (else x)))
 
 (define (ast-collect f x)
@@ -46,7 +50,8 @@
 		     (inner (lambda-body x)))]
     ['if (append (f x)
 		 (flat-map inner (cdr x)))]
-    ['closure (flat-map inner (caddr x))]
+    ['stack (append (f x)
+		    (inner (caddr x)))]
     [else (f x)]))
 
 (define (ast-find p x)
@@ -69,25 +74,65 @@
     ['lambda (either (p x)
 		     (inner (lambda-body x)))]
     ['if (either (p x) (any inner (cdr x)))]
+    ['stack (either (p x) (inner (caddr x)))]
     [else (p x)]))
 
-(define (let-bindings e)
-  (define (pattern-match binding body)
-    (if (eqv? (ast-type binding) 'var)
-	(list (cons binding body))
-	(let* ([constructor (car binding)]
-	       [destructor (lambda (i) (dtor-name constructor i))])
-	  (flat-map (lambda (y i)
-		      (pattern-match y `((,(destructor i) ,@body))))
-		    (cdr binding)
-		    (range 0 (length (cdr binding)))))))
-  (flat-map (lambda (x) (pattern-match (car x) (cdr x))) (cadr e)))
+(define let-bindings cadr)
 (define let-body cddr)
 
+					; (let ([(foo a b) (foo 123 345)]) a)
+					;   |
+					;   v
+					; (let ([a (foo~0 (foo 123 345)]
+                                        ;       [b (foo~1 (foo 123 345)]) a)
+(define (expand-pattern-matches program)
+  (define (go x)
+    (define (pattern-match binding)
+      (let ([binding-name (car binding)]
+	    [body (cadr binding)])
+	(if (eqv? (ast-type binding-name) 'var)
+	    (list (list binding-name body))
+	    
+	    (let* ([sum-name (car binding-name)]
+		   [destructor (lambda (i) (dtor-name sum-name i))]
+		   [products (cdr binding-name)]
+
+		   [data-layouts (program-data-layouts program)]
+
+		   [type (data-tor-type data-layouts sum-name)]
+
+		   [sums (cdr (assoc type data-layouts))]
+		   [sum (assoc sum-name sums)]
+		   
+		   [expected-number (length (cdr sum))])
+
+					; assert that we only do a let pattern match on an ADT with exactly one sum
+	      (when (not (= 1 (length sums)))
+		(error #f (format "Cannot pattern match a ~a in a let since it has ~a possible constructors"
+				  type
+				  (length sums))))
+
+					; assert that there is the correct number of bindings
+	      (when (not (= (length products)
+			    expected-number))
+		(error #f (format "Got ~a bindings: expected ~a for ~a"
+			       (length products)
+			       expected-number
+			       binding)))
+	      
+	      (flat-map (lambda (y i)
+			  (pattern-match (list y `(,(destructor i) ,body))))
+			products
+			(range 0 (length products)))))))
+    (case (ast-type x)
+      ['let `(let ,(flat-map pattern-match (let-bindings x))
+	       ,@(map go (let-body x)))]
+      [else (ast-traverse go x)]))
+  (program-map-exprs go program))
+
 (define (lambda? x)
   (and (list? x) (eq? (car x) 'lambda)))
 
-
 (define (statement-type x)
   (cond
    [(and (list? x)
@@ -96,36 +141,49 @@
 	 (eqv? (car x) 'define)) 'define]
    [else 'expr]))
 
-(define (program-datas program)
-  (filter (lambda (x) (eqv? (statement-type x) 'data))
-	  program))
+
+					; (A ((foo (Int Bool))
+					;     (bar (Bool)))
+(define (program-data-layouts program)
+  (map (lambda (x) (cons (car x) (cdr x))) ; convert to assoc list
+       (map cdr (filter (lambda (x) (eqv? (statement-type x) 'data))
+			program))))
 
 (define (program-defines program)
   (filter (lambda (x) (eqv? (statement-type x) 'defines))
 	  program))
 
+(define (program-map-exprs f program)
+  (map (lambda (x)
+	 (case (statement-type x)
+	   ['expr (f x)]
+	   [else x]))
+       program))
+
 (define (program-body program)
   ; hack to have multi-expression bodies
   `(let ()
      ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
 	       program)))
 
+(define (data-tor-type data-layouts tor)
+  (let* ([tors (flat-map data-tors data-layouts)]
+	 [info (cadr (assoc tor tors))])
+    (car info)))
 
-					; (A ((foo (Int Bool))
-					;     (bar (Bool)))
-
-(define data-layout cdr)
-
-					; gets both constructors and destructors
+					; a data tor is either a constructor or destructor for an ADT
+					; data-tors returns constructors and destructors for a data-layout
 					; (data A (foo Int Bool)
 					;         (bar Bool))
 					;        |
 					;        v
-					; (foo . (constructor . (abs Int (abs Bool A))))
-					; (foo~0 . (0 . (abs A Int)))
-					; (foo~1 . (1 . (abs A Bool)))
-					; (bar . (constructor . (abs Bool A)))
-					; (bar~0 . (0 . (abs A Bool)))
+					; (foo   . ((A foo constructor) . (abs Int (abs Bool A))))
+					; (foo~0 . ((A foo 0)           . (abs A Int)))
+					; (foo~1 . ((A foo 1)           . (abs A Bool)))
+					; (bar   . ((A bar constructor) . (abs Bool A)))
+					; (bar~0 . ((A bar 0)           . (abs A Bool)))
+					;  ------+-------------------------------------
+					;  tor   | info                 | type
 
 (define (data-tors data-layout)
   (define (constructor-type t products)
@@ -133,7 +191,7 @@
 
   (define (destructor ctor-name prod-type part-type index)
     (let ([name (dtor-name ctor-name index)])
-      (cons name (cons index `(abs ,prod-type ,part-type)))))
+      (cons name (cons (list prod-type ctor-name index) `(abs ,prod-type ,part-type)))))
   
   (let ([type-name (car data-layout)]
         [ctors (cdr data-layout)])
@@ -142,18 +200,17 @@
        (let* ([ctor-name (car ctor)]
 	      [products (cdr ctor)]
 	      
-	      [maker (cons ctor-name (cons 'constructor (constructor-type type-name products)))]
+	      [maker (cons ctor-name (cons (list type-name ctor-name 'constructor) (constructor-type type-name products)))]
 	      
 	      [dtors (map (lambda (t i) (destructor ctor-name type-name t i))
 			  products
 			  (range 0 (length products)))])
-	 
 	 (cons maker (append dtors acc))))
      '()
      ctors)))
 
 					; creates a type environment for a given adt definition
-(define (data-tors-env data-layout)
+(define (data-tors-type-env data-layout)
   (map (lambda (x) (cons (car x) (cddr x))) (data-tors data-layout)))
 
 (define (dtor-name ctor-name index)
@@ -274,26 +331,3 @@
 	   (strong-connect v)))
        (car graph)))
     result))
-
-
-					; utils
-
-(define (range s n)
-  (if (= 0 n) '()
-      (append (range s (- n 1))
-	      (list (+ s (- n 1))))))
-
-(define (flat-map f . xs) (fold-left append '() (apply map (cons f xs))))
-(define (repeat x n) (if (<= n 0) '()
-			 (cons x (repeat x (- n 1)))))
-
-
-(define-syntax push!
-  (syntax-rules ()
-    ((_ s x) (set! s (cons x s)))))
-
-(define-syntax pop!
-  (syntax-rules ()
-    ((_ s) (let ([x (car s)])
-	     (set! s (cdr s))
-	     x))))