Bug #3525: Enumerable#flat_map does not return a flatted enumerable

• Status: Rejected
• Assignee: -
• Target version: 1.9.2
• ruby -v: ruby 1.9.2dev (2010-07-02 revision 28524) [i686-linux]

[rbjl (Jan Lelis)]

=begin
Hi,

the new flat_map method does not return flatted enumerables:

irb(main):072:0> [[1,2],2,3].flat_map{|e|e}
=> [1, 2, 2, 3]
irb(main):071:0> [[1,2],2,3].flat_map.to_a
=> [[1, 2], 2, 3]
=end

[mame (Yusuke Endoh)]

• Status changed from Open to Rejected

=begin
Hi,

2010/7/3 Jan Lelis [e-mail]:

the new flat_map method does not return flatted enumerables:

irb(main):072:0> [[1,2],2,3].flat_map{|e|e}
=> [1, 2, 2, 3]
irb(main):071:0> [[1,2],2,3].flat_map.to_a
=> [[1, 2], 2, 3]

It is indeed confusing a little, but not a bug.

Enumerable#flat_map aggregates values that is returned from block call,
and returns a flattend array of these values.

Enumerator#to_a aggregates arguments that is passed to (implicit) block
and just returns it as an array.

Look and consider the result of [[1,2],2,3].reject.to_a.

--
Yusuke Endoh [e-mail]
=end