add sets

1 files changed, 60 insertions, 0 deletions

diff --git a/miniscm/init.scm b/miniscm/init.scm
index c3f5612..91abe72 100644
--- a/miniscm/init.scm
+++ b/miniscm/init.scm
@@ -114,3 +114,63 @@
                        (if (< (char->integer x) (char->integer y))
                            '<
                            '>))))))
+
+(define max
+  (lambda (curmax . rest)
+    (if (null? rest)
+        curmax
+        (let ((next-num (car rest)))
+          (apply max
+                 (cons (if (> next-num curmax) next-num curmax)
+                       (cdr rest)))))))
+
+(define all
+  (lambda (f l)
+    (cond
+      ((null? l) #t)
+      ((not (f (car l))) (all f (cdr l)))
+      (else #f))))
+
+(define any
+  (lambda (f l)
+    (cond
+      ((null? l) #f)
+      ((f (car l)) #t)
+      (else (any f (cdr l))))))
+
+(macro
+ cond-expand
+ (lambda (body)
+   (letrec
+       ((loop
+         (lambda (body)
+           (if (null? body)
+               #f
+               (let ((elem (car body)))
+                 (cond
+                   ((eqv? (car elem) 'else)
+                    (cons 'begin (cdr elem)))
+                   ((and (pair? elem)
+                         (passes? (car elem)))
+                    (cons 'begin (cdr elem)))
+                   (else (loop (cdr body))))))))
+        (passes?
+         (lambda (boolean-form)
+           (cond
+             ((eqv? boolean-form 'miniscm-unslisp) #t)
+             ((eqv? boolean-form 'r3rs) #t)
+             ((symbol? boolean-form) #f)
+             ((not (pair? boolean-form)) (error "invalid boolean form"))
+             ((eqv? (car boolean-form) 'and)
+              (all passes? (cdr boolean-form)))
+             ((eqv? (car boolean-form) 'or)
+              (any passes? (cdr boolean-form)))
+             ((eqv? (car boolean-form) 'not)
+              (not (passes? (cadr boolean-form))))
+             (else (error "invalid boolean function"))))))
+     (loop (cdr body)))))
+
+(define (abs x)
+  (if (< x 0)
+      (- x)
+      x))