all tasks

Task/Y-combinator/GAP/y-combinator.gap

@@ -0,0 +1,35 @@
+Y := function(f)
+    local u;
+    u := x -> x(x);
+    return u(y -> f(a -> y(y)(a)));
+end;
+
+fib := function(f)
+    local u;
+    u := function(n)
+        if n < 2 then
+            return n;
+        else
+            return f(n-1) + f(n-2);
+        fi;
+    end;
+    return u;
+end;
+
+Y(fib)(10);
+# 55
+
+fac := function(f)
+    local u;
+    u := function(n)
+        if n < 2 then
+            return 1;
+        else
+            return n*f(n-1);
+        fi;
+    end;
+    return u;
+end;
+
+Y(fac)(8);
+# 40320