Implemented let*

[scheme.forth.jl.git] / src / scheme-library.scm

diff --git a/src/scheme-library.scm b/src/scheme-library.scm
index 68debca..a420c70 100644 (file)
--- a/src/scheme-library.scm
+++ b/src/scheme-library.scm
@@ -12,8 +12,34 @@
 (define (cadr l) (car (cdr l)))
 (define (cdar l) (cdr (car l)))
 (define (cddr l) (cdr (cdr l)))
+(define (caaar l) (car (car (car l))))
+(define (caadr l) (car (car (cdr l))))
 (define (cadar l) (car (cdr (car l))))
+(define (caddr l) (car (cdr (cdr l))))
+(define (cdaar l) (cdr (car (car l))))
+(define (cdadr l) (cdr (car (cdr l))))
+(define (cddar l) (cdr (cdr (car l))))
+(define (cdddr l) (cdr (cdr (cdr l))))
+(define (cadddr l) (car (cdr (cdr (cdr l)))))
 
+;; FUNCTIONAL PROGRAMMING
+
+(define (fold-left proc init l)
+  (if (null? l)
+    init
+    (fold-left proc (proc init (car l)) (cdr l))))
+
+(define (reduce-left proc init l)
+  (if (null? l)
+    init
+    (if (null? (cdr l))
+      (car l)
+      (fold-left proc (proc (car l) (car (cdr l))) (cdr (cdr l))))))
+
+(define (map proc l)
+  (if (null? l)
+    '()
+    (cons (proc (car l)) (map proc (cdr l)))))
 
 ;; NUMBERS
 
@@ -118,18 +144,6 @@
 (define (null? arg)
   (eq? arg '()))
 
-(define (fold-left proc init l)
-  (if (null? l)
-    init
-    (fold-left proc (proc init (car l)) (cdr l))))
-
-(define (reduce-left proc init l)
-  (if (null? l)
-    init
-    (if (null? (cdr l))
-      (car l)
-      (fold-left proc (proc (car l) (car (cdr l))) (cdr (cdr l))))))
-
 (define (+ . args)
   (fold-left pair+ 0 args))
 
@@ -195,6 +209,10 @@
 (define (integer? x) (= x (round x)))
 (define (exact? x) (fixnum? x))
 (define (inexact? x) (flonum? x))
+(define (number? x)
+  (if (fixnum? x) #t
+    (if (flonum? x) #t
+      (if (ratnum? x) #t #f))))
 
 ;; LISTS
 
@@ -203,7 +221,7 @@
   (define (iter a count)
     (if (null? a)
       count
-      (iter (cdr a) (+ count 1))))
+      (iter (cdr a) (fix:+ count 1))))
   (iter l 0))
 
 ; Join two lists together
@@ -231,19 +249,17 @@
 
 ; let
 
-(define (let-vars args)
-  (if (null? args)
-    '()
-    (cons (caar args) (let-vars (cdr args)))))
+(define-macro (let args . body)
+              `((lambda ,(map (lambda (x) (car x)) args)
+                 ,@body) ,@(map (lambda (x) (cadr x)) args)))
 
-(define (let-inits args)
-  (if (null? args)
-    '()
-  (cons (cadar args) (let-inits (cdr args)))))
+; let*
 
-(define-macro (let args . body)
-              `((lambda ,(let-vars args)
-                 ,@body) ,@(let-inits args)))
+(define-macro (let* args . body)
+              (if (null? args)
+                `(let () ,@body)
+                `(let (,(car args))
+                   (let* ,(cdr args) ,@body))))
 
 ; while
 
@@ -257,60 +273,66 @@
 
 ; cond
 
-(define (cond-predicate clause) (car clause))
-(define (cond-actions clause) (cdr clause))
-(define (cond-else-clause? clause)
-  (eq? (cond-predicate clause) 'else))
-
-(define (expand-clauses clauses)
-  (if (null? clauses)
-    (none)
-    (let ((first (car clauses))
-          (rest (cdr clauses)))
-      (if (cond-else-clause? first)
-        (if (null? rest)
-          `(begin ,@(cond-actions first))
-          (error "else clause isn't last in cond expression."))
-        `(if ,(cond-predicate first)
-           (begin ,@(cond-actions first))
-           ,(expand-clauses rest))))))
-
-(define-macro (cond . clauses)
-              (if (null? clauses)
-                (error "cond requires at least one clause.")
-                (expand-clauses clauses)))
+((lambda ()
+   (define (cond-predicate clause) (car clause))
+   (define (cond-actions clause) (cdr clause))
+   (define (cond-else-clause? clause)
+     (eq? (cond-predicate clause) 'else))
+
+   (define (expand-clauses clauses)
+     (if (null? clauses)
+       (none)
+       (let ((first (car clauses))
+             (rest (cdr clauses)))
+         (if (cond-else-clause? first)
+           (if (null? rest)
+             `(begin ,@(cond-actions first))
+             (error "else clause isn't last in cond expression."))
+           `(if ,(cond-predicate first)
+              (begin ,@(cond-actions first))
+              ,(expand-clauses rest))))))
+
+   (define-macro (cond . clauses)
+                 (if (null? clauses)
+                   (error "cond requires at least one clause.")
+                   (expand-clauses clauses)))
+   ))
 
 ; and
 
-(define (expand-and-expressions expressions)
-  (let ((first (car expressions))
-        (rest (cdr expressions)))
-    (if (null? rest)
-      first
-      `(if ,first
-         ,(expand-and-expressions rest)
-         #f))))
-
-(define-macro (and . expressions)
-              (if (null? expressions)
-                #t
-                (expand-and-expressions expressions)))
+((lambda ()
+   (define (expand-and-expressions expressions)
+     (let ((first (car expressions))
+           (rest (cdr expressions)))
+       (if (null? rest)
+         first
+         `(if ,first
+            ,(expand-and-expressions rest)
+            #f))))
+
+   (define-macro (and . expressions)
+                 (if (null? expressions)
+                   #t
+                   (expand-and-expressions expressions)))
+   ))
 
 ; or
 
-(define (expand-or-expressions expressions)
-  (if (null? expressions)
-    #f
-    (let ((first (car expressions))
-          (rest (cdr expressions))
-          (val (gensym)))
-      `(let ((,val ,first))
-         (if ,val
-            ,val
-            ,(expand-or-expressions rest))))))
+((lambda ()
+   (define (expand-or-expressions expressions)
+     (if (null? expressions)
+       #f
+       (let ((first (car expressions))
+             (rest (cdr expressions))
+             (val (gensym)))
+         `(let ((,val ,first))
+            (if ,val
+              ,val
+              ,(expand-or-expressions rest))))))
 
-(define-macro (or . expressions)
-              (expand-or-expressions expressions))
+   (define-macro (or . expressions)
+                 (expand-or-expressions expressions))
+   ))
 
 
 ;; TESTING
@@ -330,18 +352,18 @@
 (define (sum n)
 
   (define (sum-iter total count maxcount)
-    (if (> count maxcount)
+    (if (fix:> count maxcount)
       total
-      (sum-iter (+ total count) (+ count 1) maxcount)))
+      (sum-iter (fix:+ total count) (fix:+ count 1) maxcount)))
   
   (sum-iter 0 1 n))
 
 ; Recursive summation. Use this to compare with tail call
 ; optimized iterative algorithm.
 (define (sum-recurse n)
-  (if (= n 0)
+  (if (fix:= n 0)
     0
-    (+ n (sum-recurse (- n 1)))))
+    (fix:+ n (sum-recurse (fix:- n 1)))))
 
 ;; MISC