Initial data commit

Task/Y-combinator/Objective-C/y-combinator-1.m

@@ -0,0 +1,41 @@
+#import <Foundation/Foundation.h>
+
+typedef int (^Func)(int);
+typedef Func (^FuncFunc)(Func);
+typedef Func (^RecursiveFunc)(id); // hide recursive typing behind dynamic typing
+
+Func Y(FuncFunc f) {
+  RecursiveFunc r =
+  ^(id y) {
+    RecursiveFunc w = y; // cast value back into desired type
+    return f(^(int x) {
+      return w(w)(x);
+    });
+  };
+  return r(r);
+}
+
+int main (int argc, const char *argv[]) {
+  @autoreleasepool {
+
+    Func fib = Y(^Func(Func f) {
+      return ^(int n) {
+        if (n <= 2) return 1;
+        return  f(n - 1) + f(n - 2);
+      };
+    });
+    Func fac = Y(^Func(Func f) {
+      return ^(int n) {
+        if (n <= 1) return 1;
+        return n * f(n - 1);
+      };
+    });
+
+    Func fib = fix(almost_fib);
+    Func fac = fix(almost_fac);
+    NSLog(@"fib(10) = %d", fib(10));
+    NSLog(@"fac(10) = %d", fac(10));
+
+  }
+  return 0;
+}

Task/Y-combinator/Objective-C/y-combinator-2.m

@@ -0,0 +1,5 @@
+Func Y(FuncFunc f) {
+  return ^(int x) {
+    return f(Y(f))(x);
+  };
+}