enumerable.md

module Enumerable

Overview

The module Enumerable is used by mixin into the class object. Now the class Range is used Enumerable by mixin.

Interfaces

The interfaces of Enumerable can be used by the class which doing mixin the Enumerable module. For example, the Range can also use the following interfaces.

Lazy field means the lazy operation will be performed after you call lazy() and use the Enumerator object returned by lazy().

Name	Outline	Lazy
filter(func)	Filters by the element returned by func.	O
map(func)	Maps by the element returned by func.	O
flatMap(func)	Maps by the element returned by func, then flatten the all result.	O
take(n)	Takes n elements from the beginning.	O
takeWhile(func)	Takes an element while returning true by func.	O
drop(n)	Skips n elements from the beginning.	O
dropWhile(func)	Skips an element while returning true by func.	O
each(func)	Applies func for each.	O
reduce(func, initer)	Reduces by the result of func. initer is the initial value if necessary.
sort(func)	Sorts elements by comparing with the result of func
all(func)	true if the result of func is all true for all elements.
any(func)	true if there is at least one element which is true returned by func.
toArray()	Returns elements as Array.
println()	Applies System.println for all elements.
lazy()	Returns Enumerator for lazy operation.

Examples

Example 1. filter

Code

System.println((2..10).filter(&(e) => e % 2));

Result

[3, 5, 7, 9]

Example 2. map

Code

(2..10).map(&(e) => e**e).each(&(e) => System.println(e));

Result

4
27
256
3125
46656
823543
16777216
387420489
10000000000

Example 3. flatMap

Code

(2..10).flatMap(&(e) => [e, e**2]).each(&(e) => System.println(e));

Result

2
4
3
9
4
16
5
25
6
36
7
49
8
64
9
81
10
100

Example 4. take

Code

(2..10).take(5).each(&(e) => System.println(e));

Result

2
3
4
5
6

Example 5. takeWhile

Code

(2..10).takeWhile(&(e) => e < 4).each(&(e) => System.println(e));

Result

2
3

Example 6. drop

Code

(2..10).drop(5).each(&(e) => System.println(e));

Result

7
8
9
10

Example 7. dropWhile

Code

(2..10).dropWhile(&(e) => e < 4).each(&(e) => System.println(e));

Result

4
5
6
7
8
9
10

Example 8. each

Code

(2..10).each(&(e) => System.println(e));

Result

2
3
4
5
6
7
8
9
10

Example 9 reduce

Code

System.println((2..10).reduce(&(r, e) => r + e));
System.println((2..10).reduce(&(r, e) => r + e, 1));

Result

54
55

Example 10. sort

Code

System.println((2..10).sort(&(e1, e2) => e1 <=> e2));
System.println((2..10).sort(&(e1, e2) => e2 <=> e1));

Result

[2, 3, 4, 5, 6, 7, 8, 9, 10]
[10, 9, 8, 7, 6, 5, 4, 3, 2]

Example 11. all

Code

System.println((2..10).all(&(e) => e < 3));
System.println((2..10).all(&(e) => e <= 10));

Result

0
1

Example 12. any

Code

System.println((2..10).any(&(e) => e == 3));
System.println((2..10).any(&(e) => e == 13));

Result

1
0

Example 13. toArray

Code

System.println((2..10).toArray());

Result

[2, 3, 4, 5, 6, 7, 8, 9, 10]

Example 14. println

Code

(2..10)
    .takeWhile(&(e) => e < 4)
    .println();

Result

2
3

Example 15. lazy

Code

(2..10).lazy()
    .filter(&(e) => e % 2)
    .take(3)
    .println();

Result

3
5
7