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@alexrothenberg
Created March 6, 2014 16:31
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MRI/JRuby/Rubinius discrepency
MRI - detect with a lambda complains about 2 parameters but map works
$ irb
2.1.1 :001 > lambda = ->(word, index) { word.length == 3 }
=> #<Proc:0x007fb52d00ab38@(irb):1 (lambda)>
2.1.1 :002 > %w(Hi there how are you).each_with_index.detect &lambda
ArgumentError: wrong number of arguments (1 for 2)
from (irb):1:in `block in irb_binding'
from (irb):2:in `each'
from (irb):2:in `each_with_index'
from (irb):2:in `each'
from (irb):2:in `detect'
from (irb):2
from /Users/alex/.rvm/rubies/ruby-2.1.1/bin/irb:11:in `<main>'
2.1.1 :003 > %w(Hi there how are you).each_with_index.map &lambda
=> [false, false, true, true, true]
JRuby - detect and map both work
$ jirb
jruby-1.7.10 :001 > lambda = ->(word, index) { word.length == 3 }
=> #<Proc:0x46c95759@(irb):1 (lambda)>
jruby-1.7.10 :002 > %w(Hi there how are you).each_with_index.detect &lambda
=> ["how", 2]
jruby-1.7.10 :003 > %w(Hi there how are you).each_with_index.map &lambda
=> [false, false, true, true, true]
Rubinius - detect and map both work
$ irb
rbx-2.2.3 :001 > lambda = ->(word, index) { word.length == 3 }
=> #<Proc:0x2c8c@(irb):1 (lambda)>
rbx-2.2.3 :002 > %w(Hi there how are you).each_with_index.detect &lambda
=> ["how", 2]
rbx-2.2.3 :003 > %w(Hi there how are you).each_with_index.map &lambda
=> [false, false, true, true, true]
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