Feature request: tuple expansion in blocks

[colinmarc]

Sorry if this has already been brought up somewhere.

In ruby, all of the following three snippets of code produce the same output:

arr = (0..10).each_cons(2)
arr.each { |a, b| puts "from #{a} to #{b}" }

(0..10).each_cons(2) { |a, b| puts "from #{a} to #{b}" }

(0..10).each_cons(2) { |tuple| puts "from #{tuple[0]} to #{tuple[1]}" }

Crystal, however, is missing some functionality. The first and third work, but not the second; and the first works only because there's a separate implementation for each_cons (and each_with_index, Hash#each, etc) in order to yield two values.

I'm not sure what exactly the right solution is; but since we automatically compact multiple yield values, as in the third example above, I think it would be a reasonable feature to automatically expand them to the right arity, as well.

[bcardiff]

Hi,

The issue in github is this one
#392
Splat a tuple when yielding is not supported yet.

Feel free to +1 it ;-)

On Tue, Sep 8, 2015 at 10:07 AM, Colin Marc notifications@github.com
wrote:

Sorry if this has already been brought up somewhere.

In ruby, all of the following three snippets of code produce the same
output:

a = (0..10).each_cons(2)
a.each { |a, b| puts "from #{a} to #{b}" }

(0..10).each_cons(2) { |a, b| puts "from #{a} to #{b}" }

(0..10).each_cons(2) { |tuple| puts "from #{tuple[0]} to #{tuple[1]}" }

Crystal, however, is missing some functionality. The first and third work,
but not the second; and the first works only because there's a separate
implementation for each_cons (and each_with_index, Hash#each, etc) in
order to yield two values.

I'm not sure what exactly the right solution is; but since we
automatically compact multiple yield values, as in the third example
above, I think it would be a reasonable feature to automatically expand
them to the right arity, as well.

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[jhass]

Closing as a duplicate.

[colinmarc]

Cool, I will +1 that one =). FWIW, though, that's not exactly the same as what I'm describing - this would work without splatting anything (as it does in ruby).

[jhass]

Well, we're pretty aware of autosplat and the lack thereof, just undecided on whether to do that or explicit destructing (#132) ;)

[colinmarc]

Ah, that's much more what I was getting at. Thanks for the link! =)