pyrtsa · February 24, 2015 07:55 · Feb 24, 2015
diff --git a/foldr.swift b/foldr.swift
@@ -0,0 +1,12 @@
+func foldr<A : SequenceType, B>(xs: A, y: B, f: (A.Generator.Element, () -> B) -> B) -> B { 
+    var g = xs.generate() 
+    var next: () -> B = {y} 
+    next = { return g.next().map {x in f(x, next)} ?? y } 
+    return next() 
+} 
+
+foldr([1, 2, 3, -4, -5, 6], "") {a, b in
+    println(a)
+    return a < 0 ? toString(a) : b()
+}
+// Prints the lines 1, 2, 3, -4, and then returns "-4".