Hello, Palindrome, & Number-Guesser code-bases

1 files changed, 52 insertions, 0 deletions

diff --git a/basics.scm b/basics.scm
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+;;;; variables
+(define my-var 15)
+my-var
+
+;; set to something else
+(set! my-var 20)
+
+;;;; functions
+(define (find value lst)
+  (if (pair? lst)
+      (begin
+        (display (string-append "Looking at: " (number->string (car lst))
+                                "\n"))
+        (if (equal? (car lst) value)
+            (begin (display "Found it!\n")
+                   (car lst))
+            (find value (cdr lst))))
+      #f))
+
+(find 5 '(1 2 3 4 5 6))
+
+;; note that variables and functions exist in the same
+;; namespace, and that we can define functions in a
+;; slightly more ugly way, but looks a lot like a var
+;; declaration:
+(define find-x (lambda (value lst)
+                 (if (pair? lst)
+                     (begin
+                       (display (string-append "Looking at: " (number->string (car lst))
+                                               "\n"))
+                       (if (equal? (car lst) value)
+                           (begin (display "Found it!\n")
+                                  (car lst))
+                           (find value (cdr lst))))
+                     #f)))
+
+(find-x 4 '(1 2 3 4 5 6))
+
+;;;; let
+
+;; let as a looping construct
+(let find-loop ((value 5)
+                (lst '(1 2 3 4 5)))
+  (if (pair? lst)
+      (begin
+        (display (string-append "Looking at: " (number->string (car lst))
+                                "\n"))
+        (if (equal? (car lst) value)
+            (begin (display "Found it!\n")
+                   (car lst))
+            (find-loop value (cdr lst))))
+      #f))