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Feature #16102

open

`Symbol#call`

Added by sawa (Tsuyoshi Sawada) over 2 years ago. Updated about 2 years ago.

Status:
Open
Priority:
Normal
Assignee:
-
Target version:
-
[ruby-core:94342]

Description

Since symbols have a to_proc method, it is natural to expect that they would appear in a method chain like:

:some_symbol.to_proc.call(...)

In fact, I have use cases like this:

arrays = [["a", "b"], ["c"], ["d", "e"]]
hashes = [{"a" => 1}, {"b" => 2, "c" => 3}, {"d" => 4, "e" => 5}]

:product.to_proc.(*arrays) # => [["a", "c", "d"], ["a", "c", "e"], ["b", "c", "d"], ["b", "c", "e"]]
:zip.to_proc.(*arrays) # => [["a", "c", "d"], ["b", nil, "e"]]
:union.to_proc.(*arrays) # => ["a", "b", "c", "d", "e"]
:merge.to_proc.(*hashes) # => {"a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5}

I request Symbol#call to be defined, which would implicitly call to_proc on the receiver and then the conventional Proc#call on the result. Then, I can do:

:product.(*arrays) # => [["a", "c", "d"], ["a", "c", "e"], ["b", "c", "d"], ["b", "c", "e"]]
:zip.(*arrays) # => [["a", "c", "d"], ["b", nil, "e"]]
:union.(*arrays) # => ["a", "b", "c", "d", "e"]
:merge.(*hashes) # => {"a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5}

This would solve what proposals #6499, #6727, #7444, #8970, #11262 aim to do.

Notice that proposals #12115 and #15301 ask for Symbol#call, but they ask for different things (a method that returns a proc), and are irrelevant to the current proposal.

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