Iteration

import std.algorithm.iteration;

• map (array, func) -> any |

  • Returns: an new array where each element at index i is equals to the result of func (array [i])
  • Parameters :
    • array, an array of element
    • func, an function fn (x)-> y, where x has the same type as an element of array
  • Example:

    let a = ([1, 2, 3]).map (fn (x) => x + 1);
    assert (a == [2, 3, 4]);
    

• each (array, func)-> void | Call the function func on each element of array

  • Parameters:
    • array, an array of element
    • func, a function fn (x)-> void, where x has the same type as an element of array
  • Example:

    let a = [1, 2, 3];
    a.each (fn (x) => println (x)); // 1 2 3
    

• scan (array, func)-> any | Perform a scan operation, i.e a cumulative reduction of array

  • Parameters:
    • array, an array of element
    • func, a function fn (x, y)-> z, where x, y and z have the same type as an element of array
  • Example:

    let a = [1, 2, 3];
    let b = a.scan (fn (x, y) => x + y);
    assert (b == [1, 3, 6]); // [1, 1 + 2, 1 + 2 + 3]
    

• filter (array, func)-> any | Filter an array of element using a predicate
  • Parameters :
    • array, an array of element
    • func, a function fn (x)-> bool, where x has the same type as an element of array
  • Example:

    let a = [1, 2, 3, 4];
    let b = a.filter (fn (x) => x % 2 == 1);
    assert (b == [1, 3]);
    

• reduce (array, func)-> any | Reducing an array to a single value
  • Parameters :
    • array, an array of element
    • func, a function fn (x, y)-> z, where x, y and z have the same type as an element of array
  • Example:

    let a = [1, 2, 3, 4];
    let b = a.reduce (fn (x, y) => a + b);
    assert (b == 10);
    

• zip (a, b, func)-> any Same as a map operation but use two array
  • Parameters:
    • a, an array of element
    • b, an array of element
    • func, a function fn (x, y)-> z, where x has the same type as an element of a and y has the same type as an element of b
  • Example:

    let a = [1, 2, 3];
    let b = ["one", "two", "three"];
    let c = zip (a, b, fn (x, y) => (x, y));
    assert (c == [(1, "one"), (2, "two"), (3, "three")])