Data commit

Task/Mutual-recursion/Oberon-2/mutual-recursion.oberon

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+MODULE MutualRecursion;
+
+  IMPORT Out;
+
+  TYPE
+    Fn = PROCEDURE(n:INTEGER):INTEGER;
+
+  PROCEDURE^ M(n:INTEGER):INTEGER;
+
+  PROCEDURE F(n:INTEGER):INTEGER;
+  BEGIN
+    IF n=0 THEN RETURN 1
+    ELSE RETURN n-M(F(n-1))
+    END;
+  END F;
+
+  PROCEDURE M(n:INTEGER):INTEGER;
+  BEGIN
+    IF n=0 THEN RETURN 0
+    ELSE RETURN n-F(M(n-1))
+    END;
+  END M;
+
+(* Print the first few values of one of the functions *)
+  PROCEDURE Show(name:ARRAY OF CHAR;fn:Fn);
+    CONST Max = 15;
+    VAR i:INTEGER;
+  BEGIN
+    Out.String(name);
+    Out.String(": ");
+    FOR i := 0 TO Max DO
+      Out.Int(fn(i),0);
+      Out.String(" ");
+    END;
+    Out.Ln;
+  END Show;
+
+(* Show the first values of both F and M *)
+BEGIN
+  Show("F", F);
+  Show("M", M);
+END MutualRecursion.