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Groups > comp.lang.ruby > #7392

reduce, map, :+ and :upcase as blocks and symbols as arguments

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Why does `reduce' work passing both `&:+' _and_ `:+', but `map' seems to
accept only `&:upcase' (but not `:upcase`)?

>> (1..5).reduce(:+)
=> 15
>> (1..5).reduce(&:+)
=> 15
>> ['x', 'y', 'z'].map(:upcase)
ArgumentError: wrong number of arguments (given 1, expected 0)
from (pry):3:in `map'
>> ['x', 'y', 'z'].map(&:upcase)
=> ["X", "Y", "Z"]

Docs for `Enumerable#reduce' say:

""
Combines all elements of enum by applying a binary
operation, specified by a block or a symbol that names a
method or operator.
""

Docs `Enumerable#map' say:

""
Returns a new array with the results of running block once
for every element in enum.
""

So, is that `reduce' takes both a block and a symbol, while map takes
only a block? And if so, is that some Ruby inconsistency?

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Thread

reduce, map, :+ and :upcase as blocks and symbols as arguments Fernando Basso <fernanodobasso.br@gmail.com> - 2018-06-28 06:25 -0300
  Re: reduce, map, :+ and :upcase as blocks and symbols as arguments Robert Klemme <shortcutter@googlemail.com> - 2018-07-05 08:23 +0200
    Re: reduce, map, :+ and :upcase as blocks and symbols as arguments Fernando Basso <fernanodobasso.br@gmail.com> - 2018-07-05 07:01 -0300

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