1 files changed, 32 insertions, 0 deletions
diff --git a/prescheme-nim-local/lib/ps-utils.scm b/prescheme-nim-local/lib/ps-utils.scm
new file mode 100644
index 0000000..574bb04
--- /dev/null
+++ b/prescheme-nim-local/lib/ps-utils.scm
@@ -0,0 +1,32 @@
+;;; ps-utils --- Utilities for Pre-Scheme
+
+(define-syntax when
+  (syntax-rules ()
+    ((_ condition consequent ...)
+     (if condition
+         (begin consequent ...)))))
+
+(define-syntax unless
+  (syntax-rules ()
+    ((_ condition antecedent ...)
+     (if (not condition)
+         (begin antecedent ...)))))
+
+(define-syntax define-wrapper-type
+  (lambda (exp rename compare)
+    (define (symbol-append . args)
+      (string->symbol
+       (apply string-append (map (lambda (s)
+                                   (if (string? s) s (symbol->string s)))
+                                 args))))
+    (let* ((name (cadr exp))
+           (type-id (symbol-append ":" name))
+           (constructor (rename (symbol-append "make-" name)))
+           (%begin (rename 'begin))
+           (%define-record-type (rename 'define-record-type))
+           (%define-external (rename 'define-external)))
+      `(,%define-record-type ,name ,type-id
+        (,constructor)))))
+
+(define (zero? n) (= n 0))
+(define (one? n) (= n 1))