module Enumerable(T)

Overview

The Enumerable mixin provides collection classes with several traversal, searching, filtering and querying methods.

Including types must provide an each method, which yields successive members of the collection.

For example:

class Three
  include Enumerable(Int32)

  def each(&)
    yield 1
    yield 2
    yield 3
  end
end

three = Three.new
three.to_a                # => [1, 2, 3]
three.select &.odd?       # => [1, 3]
three.all? { |x| x < 10 } # => true

Note that most search and filter methods traverse an Enumerable eagerly, producing an Array as the result. For a lazy alternative refer to the Iterator and Iterable modules.

Direct including types

Defined in:

permafrost/ext.cr

Instance Method Summary

Instance Method Detail

def to_pf_bidi #

Like #to_pf_map, but creates a Pf::BidiMap.

(0...10).zip('a'...'z').to_pf_bidi # => Pf::BidiMap{0 <=> 'a', 1 <=> 'b', 2 <=> 'c', ...}

[View source]
def to_pf_map(& : T -> Tuple(K, V)) : Pf::Map(K, V) forall K, V #

Creates a Pf::Map out of {key, value} tuple pairs returned by the block.

(0...10).to_pf_map { |n| {n, n * 2} } # => Pf::Map{2 => 4, 3 => 6, 4 => 8, ...}

[View source]
def to_pf_map #

Creates a Pf::Map out of an Enumerable whose elements respond to .[0] and .[1].

(0...10).zip('a'..'z').to_pf_map # => Pf::Map{0 => 'a', 1 => 'b', 2 => 'c', ...}

[View source]
def to_pf_set : Pf::Set(T) #

Creates a Pf::Set out of an Enumerable.

(0...5).to_pf_set # => Pf::Set[0, 1, 2, 3, 4]

[View source]