Feature #9635: Map a hash directly to a hash

• Status: Closed
• Assignee: -
• Target version: -

[lolmaus (Andrey Mikhaylov)]

There should be a way to directly map a hash to a hash.

The current way to do it is not very graceful:

{foo: 'foo', bar: 'bar'}.map { |key, value| [key.upcase, value.reverse] }.to_h     # => { :FOO => 'oof', :BAR => 'rab' }

I think there should be a simpler and more natural way to do that. Something like this:

{foo: 'foo', bar: 'bar'}.hashy_map { |key, value| key.upcase => value.reverse }    # => { :FOO => 'oof', :BAR => 'rab' }

[lolmaus (Andrey Mikhaylov)]

Ok, what i suggest is not a valid Ruby syntax. It should be

.hashy_map { |key, value| {key => value} }

which is hardly sweeter than

.map { |key, value| [key, value] }.to_h

and also goes against common practice of returning multiple results in an array.

@apeiros (Stefan Rusterholz) from irc://irc.freenode.net/ruby/ has cleared this out to me and suggested this very compact and efficient implementation: https://gist.github.com/apeiros/9527275

[phluid61 (Matthew Kerwin)]

At the risk of being terse, https://bugs.ruby-lang.org/issues/7793

[shyouhei (Shyouhei Urabe)]

• Related to Feature #12512: Import Hash#transform_values and its destructive version from ActiveSupport added

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed