From: Dan Kubb Date: 2012-03-16T14:53:42+09:00 Subject: [ruby-core:43334] [ruby-trunk - Bug #6155][Open] Enumerable::Lazy#flat_map raises an exception when an element does not respond to #each Issue #6155 has been reported by Dan Kubb. ---------------------------------------- Bug #6155: Enumerable::Lazy#flat_map raises an exception when an element does not respond to #each https://bugs.ruby-lang.org/issues/6155 Author: Dan Kubb Status: Open Priority: Normal Assignee: Category: Target version: ruby -v: ruby 2.0.0dev (2012-03-15 trunk 35028) [x86_64-darwin11.3.0] The following statement will raise "NoMethodError: undefined method `each' for 1:Fixnum": [1, 2, 3].lazy.flat_map { |n| n }.to_a It appears as if Enumerable::Lazy#flat_map is calling #each on every element, regardless of whether it can work or not. As a reference, the equivalent statement using Enumerable#flat_map works: [1, 2, 3].flat_map { |n| n }.to_a -- http://bugs.ruby-lang.org/