Block Lambdas: break and continue

Brendan Eich brendan at
Sun Jan 15 23:46:58 PST 2012

> Axel Rauschmayer <mailto:axel at>
> January 15, 2012 11:32 PM
> The main problem I would have with "for" as a prefix is semantic, not 
> grammatical: I would always expect to loop over something iterable and 
> not a loop implementation.

Yes, I agree with that and it's what I meant by head-less body (or is it 
body-less head?).

But the syntactic ambiguity is a problem too.

> My impression: Let’s wait until we have a more powerful collection 
> library (which I assume would use block lambdas extensively). Then it 
> should become clear where/if people miss break and continue. A label 
> is a reasonable work-around that should even survive the insertion of 
> a “loop-ifying” keyword.

> Could we call block lambdas just lambdas? The former seems a bit 
> pleonastic.
Love that word. I didn't intend a pleonasm but I definitely felt some 
need to distinguish block-lambdas from Ruby blocks (while also giving 
them a hat tip), and from other lambda strawman proposals, especially

This looks orphaned in the wiki, so maybe there's no more chance of 
confusion. Happy to use "lambda" if I'm not stepping on someone else's toes.


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