Move expanding pattern matches to its own transformations

[scheme.git] / ast.scm

diff --git a/ast.scm b/ast.scm
index 9af36531e7ef38bb1affc652eb09c5afa46a3dcc..8a986173d675f43eb58cd0c5f7c6c7c679175d9f 100644 (file)
--- a/ast.scm
+++ b/ast.scm
@@ -75,19 +75,31 @@
     ['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 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))])
+           (flat-map (lambda (y i)
+                       (pattern-match (list y `(,(destructor i) ,body))))
+                     (cdr binding-name)
+                     (range 0 (length (cdr binding-name))))))))
+  (case (ast-type x)
+      ['let `(let ,(flat-map pattern-match (let-bindings x))
+                 ,@(map expand-pattern-matches (let-body x)))]
+      [else (ast-traverse expand-pattern-matches x)]))
+
 (define (lambda? x)
   (and (list? x) (eq? (car x) 'lambda)))
 
@@ -112,6 +124,13 @@
   (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 ()