Data commit

Task/Partial-function-application/Go/partial-function-application.go

@@ -0,0 +1,55 @@
+package main
+
+import "fmt"
+
+// Using a method bound to a function type:
+
+// fn is a simple function taking an integer and returning another.
+type fn func(int) int
+
+// fs applies fn to each argument returning all results.
+func (f fn) fs(s ...int) (r []int) {
+	for _, i := range s {
+		r = append(r, f(i))
+	}
+	return r
+}
+
+// Two simple functions for demonstration.
+func f1(i int) int { return i * 2 }
+func f2(i int) int { return i * i }
+
+// Another way:
+
+// addn returns a function that adds n to a sequence of numbers
+func addn(n int) func(...int) []int {
+	return func(s ...int) []int {
+		var r []int
+		for _, i := range s {
+			r = append(r, n+i)
+		}
+		return r
+	}
+}
+
+func main() {
+	// Turning a method into a function bound to it's reciever:
+	fsf1 := fn(f1).fs
+	fsf2 := fn(f2).fs
+	// Or using a function that returns a function:
+	fsf3 := addn(100)
+
+	s := []int{0, 1, 2, 3}
+	fmt.Println("For s =", s)
+	fmt.Println("  fsf1:", fsf1(s...))       // Called with a slice
+	fmt.Println("  fsf2:", fsf2(0, 1, 2, 3)) // ... or with individual arguments
+	fmt.Println("  fsf3:", fsf3(0, 1, 2, 3))
+	fmt.Println("  fsf2(fsf1):", fsf2(fsf1(s...)...))
+
+	s = []int{2, 4, 6, 8}
+	fmt.Println("For s =", s)
+	fmt.Println("  fsf1:", fsf1(2, 4, 6, 8))
+	fmt.Println("  fsf2:", fsf2(s...))
+	fmt.Println("  fsf3:", fsf3(s...))
+	fmt.Println("  fsf3(fsf1):", fsf3(fsf1(s...)...))
+}