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timyates/Currying.java

Last active March 7, 2020 07:11
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  1. timyates revised this gist Nov 27, 2013. 1 changed file with 45 additions and 0 deletions.
    45 changes: 45 additions & 0 deletions NativeIntCurrying.java
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    package java8tests;

    import java.util.function.IntBinaryOperator ;
    import java.util.function.IntFunction ;
    import java.util.function.IntUnaryOperator ;

    public class NativeIntCurrying {

    public void currying() {
    // Create a function that adds 2 ints
    IntBinaryOperator adder = ( a, b ) -> a + b ;

    // And a function that takes an integer and returns a function
    IntFunction<IntUnaryOperator> currier = a -> b -> adder.applyAsInt( a, b ) ;

    // Call apply 4 to currier (to get a function back)
    IntUnaryOperator curried = currier.apply( 4 ) ;

    // Results
    System.out.printf( "int curry : %d\n", curried.applyAsInt( 3 ) ) ; // ( 4 + 3 )
    }

    public void composition() {
    // A function that adds 3
    IntUnaryOperator add3 = (a) -> a + 3 ;

    // And a function that multiplies by 2
    IntUnaryOperator times2 = (a) -> a * 2 ;

    // Compose add with times
    IntUnaryOperator composedA = add3.compose( times2 ) ;

    // And compose times with add
    IntUnaryOperator composedB = times2.compose( add3 ) ;

    // Results
    System.out.printf( "int times then add: %d\n", composedA.applyAsInt( 6 ) ) ; // ( 6 * 2 ) + 3
    System.out.printf( "int add then times: %d\n", composedB.applyAsInt( 6 ) ) ; // ( 6 + 3 ) * 2
    }

    public static void main( String[] args ) {
    new NativeIntCurrying().currying() ;
    new NativeIntCurrying().composition() ;
    }
    }
  2. timyates created this gist Nov 27, 2013.
    44 changes: 44 additions & 0 deletions Currying.java
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    package java8tests ;

    import java.util.function.BiFunction ;
    import java.util.function.Function ;

    public class Currying {

    public void currying() {
    // Create a function that adds 2 integers
    BiFunction<Integer,Integer,Integer> adder = ( a, b ) -> a + b ;

    // And a function that takes an integer and returns a function
    Function<Integer,Function<Integer,Integer>> currier = a -> b -> adder.apply( a, b ) ;

    // Call apply 4 to currier (to get a function back)
    Function<Integer,Integer> curried = currier.apply( 4 ) ;

    // Results
    System.out.printf( "Curry : %d\n", curried.apply( 3 ) ) ; // ( 4 + 3 )
    }

    public void composition() {
    // A function that adds 3
    Function<Integer,Integer> add3 = (a) -> a + 3 ;

    // And a function that multiplies by 2
    Function<Integer,Integer> times2 = (a) -> a * 2 ;

    // Compose add with times
    Function<Integer,Integer> composedA = add3.compose( times2 ) ;

    // And compose times with add
    Function<Integer,Integer> composedB = times2.compose( add3 ) ;

    // Results
    System.out.printf( "Times then add: %d\n", composedA.apply( 6 ) ) ; // ( 6 * 2 ) + 3
    System.out.printf( "Add then times: %d\n", composedB.apply( 6 ) ) ; // ( 6 + 3 ) * 2
    }

    public static void main( String[] args ) {
    new Currying().currying() ;
    new Currying().composition() ;
    }
    }