added racket

2 files changed, 99 insertions, 0 deletions

diff --git a/r/racket/README.md b/r/racket/README.md
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+Download Racket version 6 or above
+
+Run by lambda-core.rkt like this: `racket lambda-core.rkt`
\ No newline at end of file
diff --git a/r/racket/lambda-core.rkt b/r/racket/lambda-core.rkt
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+++ b/r/racket/lambda-core.rkt
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+#lang racket
+
+; LOGIC
+(define _true 
+    (lambda (x) 
+        (lambda (y) x)))
+
+(define _false 
+    (lambda (x) 
+        (lambda (y) y)))
+
+(define _not
+    (lambda (b)
+        ((b _false) _true)))
+
+(define _and
+    (lambda (b1) 
+        (lambda (b2) 
+            ((b1 b2) _false))))
+
+(define _or
+    (lambda (b1)
+        (lambda (b2) 
+            ((b1 _true) b2))))
+
+
+; CHURCH NUMERALS
+(define _zero 
+    (lambda (f) 
+        (lambda (x) x)))
+
+(define _succ
+    (lambda (n)
+        (lambda (f)
+            (lambda (x) 
+                (f ((n f) x))))))
+
+(define _pred
+    (lambda (n)
+        (lambda (f)
+            (lambda (x)
+                (((n (lambda (g)
+                        (lambda (h) (h (g f)))))
+                    (lambda (u) x))
+                 (lambda (a) a))))))
+
+(define _one (_succ _zero))
+
+
+; HELPERS - not pure lambda calculus
+(define read-bool
+    (lambda (b)
+        (displayln ((b "t") "f"))))
+
+(define read-church
+    (lambda (n)
+        (displayln ((n (lambda (x) (+ x 1))) 0))))
+
+; -------------------------------------------------
+
+; EXAMPLES
+(displayln "LOGIC")
+(displayln "--------------")
+(displayln "TRUE/FALSE")
+(read-bool _true) ; t
+(read-bool _false) ; f
+
+(displayln "NOT")
+(read-bool (_not _true)) ; f
+(read-bool (_not _false)) ; t
+
+(displayln "AND")
+(read-bool ((_and _true) _true)) ; t
+(read-bool ((_and _true) _false)) ; f
+(read-bool ((_and _false) _true)) ; f
+(read-bool ((_and _false) _false)) ; f
+
+(displayln "OR")
+(read-bool ((_or _true) _true)) ; t
+(read-bool ((_or _true) _false)) ; t
+(read-bool ((_or _false) _true)) ; t
+(read-bool ((_or _false) _false)) ; f
+
+(displayln "\nCHURCH NUMERALS")
+(displayln "--------------")
+(displayln "ZERO/SUCC")
+(read-church _zero) ; 0
+(read-church (_succ _zero)) ; 1
+(read-church (_succ (_succ _zero))) ; 2
+(read-church (_succ (_succ (_succ _zero)))) ; 3
+
+(displayln "PRED")
+(read-church (_pred _one)) ; 0
+(read-church (_pred (_succ _one))) ; 1
+(read-church (_pred (_succ (_succ _one)))) ; 2
+