Add pretty printing for types

diff --git a/typecheck.scm b/typecheck.scm
index 59e652ad9da26f36906a80964c9956179ecdad9f..21b874c2fdc043b41297575d84bdd12132d559a5 100644 (file)
--- a/typecheck.scm
+++ b/typecheck.scm
@@ -1,4 +1,27 @@
 (load "ast.scm")
+
+(define (abs? t)
+  (and (list? t) (eq? (car t) 'abs)))
+
+(define (tvar? t)
+  (and (not (list? t)) (not (concrete? t)) (symbol? t)))
+
+(define (concrete? t)
+  (case t
+    ('int #t)
+    ('bool #t)
+    (else #f)))
+
+(define (pretty-type t)
+  (cond ((abs? t)
+        (string-append
+         (if (abs? (cadr t))
+             (string-append "(" (pretty-type (cadr t)) ")")
+             (pretty-type (cadr t)))
+         " -> "
+         (pretty-type (caddr t))))
+       (else (symbol->string t))))
+
                                        ; ('a, ('b, 'a))
 (define (env-lookup env n)
   (if (null? env) (error #f "empty env")                       ; it's a type equality
@@ -137,19 +160,6 @@
       res))
   (cadr (check '() (normalize prog))))
 
-
-(define (abs? t)
-  (and (list? t) (eq? (car t) 'abs)))
-
-(define (tvar? t)
-  (and (not (list? t)) (not (concrete? t)) (symbol? t)))
-
-(define (concrete? t)
-  (case t
-    ('int #t)
-    ('bool #t)
-    (else #f)))
-
                                        ; returns a list of pairs of constraints
 (define (unify a b)
   (cond ((eq? a b) '())