Bug #12809: passing a proc to Kernel#lambda does not create a lambda

• Status: Rejected
• Assignee: akr (Akira Tanaka)
• Target version: -
• ruby -v: 2.0.0-p643, 2.1.9, 2.2.5, 2.3.1p112, 2.4.0preview2
• Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN

[sylvain.joyeux (Sylvain Joyeux)]

I would expect the following:

p = proc { |a| a * 2 }
l = lambda(&p)
puts l.lambda? # => true
l.call(1, 2) # => ArgumentError

But it does not, basically l there looks very much like a non-lambda proc (another test is that a return in p would cause l.call to raise LocalJumpError)

[shyouhei (Shyouhei Urabe)]

• Status changed from Open to Assigned
• Assignee set to akr (Akira Tanaka)

[akr (Akira Tanaka)]

• Status changed from Assigned to Rejected

Current behavior is intentional design.

If "lambda" change the lambda-ness of the given block,
the author of "proc { |a| a * 2 }" can not know how the block is interpreted.
This is what the design try to avoid.

Rather, it may be possible to raise error on "lambda" with non-lambda proc object.
This is different issue, though.