Issue #20623 has been updated by eileencodes (Eileen Uchitelle). I tested this against a few versions of Ruby. In 2.7.x the first example returns `[1,2]`. But since 3.0.x it returns `1`. It also seems `cycle` isn't needed to reproduce it, so I removed that from the reproduction script. I wasn't able to get it any smaller, as `lazy` and `force` (or `to_a`) is required. ``` [1].lazy.zip([2].lazy).map do |x| puts x.inspect end.take(5).force puts "---" [1].lazy.zip([2].lazy).take(5).force.map do |x| puts x.inspect end ``` ---------------------------------------- Bug #20623: Unexpected behavior of blocks in Enumerator::Lazy#zip https://bugs.ruby-lang.org/issues/20623#change-109051 * Author: esad (Esad Hajdarevic) * Status: Open * ruby -v: 3.3.0 * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- I've stumbled upon unexpected behaviour of lazy enumerators. My example: ``` [1].cycle.lazy.zip([2].cycle.lazy).map do |x| puts x.inspect end.take(5).force puts "---" [1].cycle.lazy.zip([2].cycle.lazy).take(5).force.map do |x| puts x.inspect end ``` The outputs (and variable assignment inside the block) differs ``` 1 1 1 1 1 --- [1, 2] [1, 2] [1, 2] [1, 2] [1, 2] ``` -- https://bugs.ruby-lang.org/