Y combinator: Difference between revisions

← Older edit Newer edit →

Content deleted Content added

Inline

@@ Line 3,742: / Line 3,742: @@
 <lang M2000 Interpreter>
 Module Ycombinator {
-      \\ y() return value. no use of closure
+	\\ y() return value. no use of closure
-      y=lambda (g, x)->g(g, x)
+	y=lambda (g, x)->g(g, x)
-      Print y(lambda (g, n)->if(n=0->1, n*g(g, n-1)), 10)
+	Print y(lambda (g, n as decimal)->if(n=0->1, n*g(g, n-1)), 10)=3628800 ' true
-      Print y(lambda (g, n)->if(n<=1->n,g(g, n-1)+g(g, n-2)), 10)
+	Print y(lambda (g, n)->if(n<=1->n,g(g, n-1)+g(g, n-2)), 10)=55 ' true
-      \\ Using closure in y, y() return function
+	\\ Using closure in y, y() return function
-      y=lambda (g)->lambda g (x) -> g(g, x)
+	y=lambda (g)->lambda g (x) -> g(g, x)
-      fact=y((lambda (g, n)-> if(n=0->1, n*g(g, n-1))))
+	fact=y((lambda (g, n as decimal)-> if(n=0->1, n*g(g, n-1))))
-      Print fact(6), fact(24)
+	Print fact(6)=720, fact(24)=620448401733239439360000@
-      fib=y(lambda (g, n)->if(n<=1->n,g(g, n-1)+g(g, n-2)))
+	fib=y(lambda (g, n)->if(n<=1->n, g(g, n-1)+g(g, n-2)))
-      Print  fib(10)
+	Print  fib(10)=55
-}
+	}
 Ycombinator
 </lang>
@@ Line 3,759: / Line 3,759: @@
 <lang M2000 Interpreter>
 Module Checkit {
+	Rem {
-      \\ all lambda arguments passed by value in this example
+		all lambda arguments passed by value in this example
-      \\ There is no recursion in these lambdas
+		There is no recursion in these lambdas
-      \\ Y combinator make  argument f as closure, as a copy of f
-      \\ m(m, argument) pass as first argument a copy of m
+		Y combinator make  argument f as closure, as a copy of f
+		m(m, argument) pass as first argument a copy of m
-      \\ so never a function, here, call itself, only call a copy who get it as argument before the call.
+		so never a function, here, call itself, only call a copy who get it as argument before the call.
-      Y=lambda (f)-> {
+	}
-            =lambda f (x)->f(f,x)
+	Y=lambda (f)-> {
-      }
-      fac_step=lambda (m, n)-> {
+		=lambda f (x)->f(f,x)
+	}
-            if n<2 then {
+	fac_step=lambda (m, n)-> {
-                  =1
+		if n<2 then =1 else =n*m(m, n-1)
-            } else {
+	}
-                  =n*m(m, n-1)
+	fac=Y(fac_step)
-            }
+	fib_step=lambda (m, n)-> {
-      }
+		if n<=1 then =n else =m(m, n-1)+m(m, n-2)
-      fac=Y(fac_step)
+	}
-      fib_step=lambda (m, n)-> {
+	fib=Y(fib_step)
-            if n<=1 then {
+	For i=1 to 10 {
-                  =n
+		Print fib(i), fac(i)
-            } else {
+	}
-                  =m(m, n-1)+m(m, n-2)
-            }
-      }
-      fib=Y(fib_step)
-      For i=1 to 10
-            Print fib(i), fac(i)
-      Next i
 }
 Checkit
-// same but more compact
-Module Checkit {
-      fac=lambda (f)->{=lambda f (x)->f(f,x)}(lambda (m, n)->{=if(n<2->1,n*m(m, n-1))})
-      fib=lambda (f)->{=lambda f (x)->f(f,x)}(lambda (m, n)->{=if(n<=1->n,m(m, n-1)+m(m, n-2))})
-      For i=1 to 10
-            Print fib(i), fac(i)
-      Next i
-}
-Checkit
 Module CheckRecursion {
-    fac=lambda (n) -> {
+	fac=lambda (n) -> {
-             if n<2 then {
+		if n<2 then =1 else =n*Lambda(n-1)
+	}
-                  =1
+	fib=lambda (n) -> {
-            } else {
+		if n<=1 then =n else =lambda(n-1)+lambda(n-2)
-                  =n*Lambda(n-1)
+	}
-            }
+	For i=1 to 10:Print fib(i), fac(i):Next
-      }
-      fib=lambda (n) -> {
-            if n<=1 then {
-                  =n
-            } else {
-                  =lambda(n-1)+lambda(n-2)
-            }
-      }
-      For i=1 to 10
-            Print fib(i), fac(i)
-      Next i
 }
 CheckRecursion