Start work on case statements

diff --git a/ast.scm b/ast.scm
index 52e06bcb24d3b4783eb301c8fb657ec7f7e06071..86d522560a8012546e6a754499b1216052d8ce70 100644 (file)
--- a/ast.scm
+++ b/ast.scm
@@ -17,6 +17,7 @@
       ('if 'if)
       ('let 'let)
       ('lambda 'lambda)
+      ('case 'case)
       ('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)
@@ -35,6 +36,10 @@
     ('app (map f x))
     ('lambda `(lambda ,(lambda-args x) ,(f (lambda-body x))))
     ('if `(if ,@(map f (cdr x))))
+    ('case `(case ,(f (case-expr x))
+             ,@(map (lambda (x)
+                      (list (car x) (f (cadr x))))
+                    (case-cases x))))
     ('stack `(stack ,(cadr x) ,(f (caddr x))))
     (else x)))
 
@@ -50,6 +55,9 @@
                     (inner (lambda-body x)))]
     ['if (append (f x)
                 (flat-map inner (cdr x)))]
+    ['case (append (f x)
+                  (inner (case-expr x))
+                  (flat-map inner (map cadr (case-cases x))))]
     ['stack (append (f x)
                    (inner (caddr x)))]
     [else (f x)]))
@@ -80,6 +88,9 @@
 (define let-bindings cadr)
 (define let-body cddr)
 
+(define case-expr cadr)
+(define case-cases cddr)
+
                                        ; (let ([(foo a b) (foo 123 345)]) a)
                                        ;   |
                                        ;   v

diff --git a/tests.scm b/tests.scm
index b3e630bbffefebbe31d959e7fd17ffa22e504976..49fc2c4bc861b13de41f454a7aa2b6e6b103d8d9 100644 (file)
--- a/tests.scm
+++ b/tests.scm
@@ -278,3 +278,12 @@
             (let ([(bar (foo x)) (bar (foo 42))])
               x))
           42)
+
+(test-prog '((data Foo [a] [b] [c])
+            (let ([x b])
+              (case x
+                [a 1]
+                [b 2]
+                [c 3])))
+          2)
+