Data commit

Task/Partial-function-application/Java/partial-function-application-1.java

@@ -0,0 +1,63 @@
+import java.util.Arrays;
+
+public class PartialApplication {
+	interface IntegerFunction {
+		int call(int arg);
+	}
+
+	// Original method fs(f, s).
+	static int[] fs(IntegerFunction f, int[] s) {
+		int[] r = new int[s.length];
+		for (int i = 0; i < s.length; i++)
+			r[i] = f.call(s[i]);
+		return r;		
+	}
+
+	interface SequenceFunction {
+		int[] call(int[] arg);
+	}
+
+	// Curried method fs(f).call(s),
+	// necessary for partial application.
+	static SequenceFunction fs(final IntegerFunction f) {
+		return new SequenceFunction() {
+			public int[] call(int[] s) {
+				// Call original method.
+				return fs(f, s);
+			}
+		};
+	}
+
+	static IntegerFunction f1 = new IntegerFunction() {
+		public int call(int i) {
+			return i * 2;
+		}
+	};
+
+	static IntegerFunction f2 = new IntegerFunction() {
+		public int call(int i) {
+			return i * i;
+		}
+	};
+
+	static SequenceFunction fsf1 = fs(f1); // Partial application.
+
+	static SequenceFunction fsf2 = fs(f2);
+
+	public static void main(String[] args) {
+		int[][] sequences = {
+			{ 0, 1, 2, 3 },
+			{ 2, 4, 6, 8 },
+		};
+
+		for (int[] array : sequences) {
+			System.out.printf(
+			    "array: %s\n" +
+			    "  fsf1(array): %s\n" +
+			    "  fsf2(array): %s\n",
+			    Arrays.toString(array),
+			    Arrays.toString(fsf1.call(array)),
+			    Arrays.toString(fsf2.call(array)));
+		}
+	}
+}