Higher-order functions: Difference between revisions

=={{header|ECL}}==

<lang>//a Function prototype:

INTEGER actionPrototype(INTEGER v1, INTEGER v2) := 0;

INTEGER aveValues(INTEGER v1, INTEGER v2) := (v1 + v2) DIV 2;

INTEGER addValues(INTEGER v1, INTEGER v2) := v1 + v2;

INTEGER multiValues(INTEGER v1, INTEGER v2) := v1 * v2;

//a Function prototype using a function prototype:

INTEGER applyPrototype(INTEGER v1, actionPrototype actionFunc) := 0;

//using the Function prototype and a default value:

INTEGER applyValue2(INTEGER v1,

actionPrototype actionFunc = aveValues) :=

actionFunc(v1, v1+1)*2;

//Defining the Function parameter inline, witha default value:

INTEGER applyValue4(INTEGER v1,

INTEGER actionFunc(INTEGER v1,INTEGER v2) = aveValues)

:= actionFunc(v1, v1+1)*4;

INTEGER doApplyValue(INTEGER v1,

INTEGER actionFunc(INTEGER v1, INTEGER v2))

:= applyValue2(v1+1, actionFunc);

//producing simple results:

OUTPUT(applyValue2(1)); // 2

OUTPUT(applyValue2(2)); // 4

OUTPUT(applyValue2(1, addValues)); // 6

OUTPUT(applyValue2(2, addValues)); // 10

OUTPUT(applyValue2(1, multiValues)); // 4

OUTPUT(applyValue2(2, multiValues)); // 12

OUTPUT(doApplyValue(1, multiValues)); // 12

OUTPUT(doApplyValue(2, multiValues)); // 24

//A definition taking function parameters which themselves

//have parameters that are functions...

STRING doMany(INTEGER v1,

INTEGER firstAction(INTEGER v1,

INTEGER actionFunc(INTEGER v1,INTEGER v2)),

INTEGER secondAction(INTEGER v1,

INTEGER actionFunc(INTEGER v1,INTEGER v2)),

INTEGER actionFunc(INTEGER v1,INTEGER v2))

:= (STRING)firstAction(v1, actionFunc) + ':' + (STRING)secondaction(v1, actionFunc);

OUTPUT(doMany(1, applyValue2, applyValue4, addValues));

// produces "6:12"

OUTPUT(doMany(2, applyValue4, applyValue2,multiValues));

// produces "24:12"</lang>