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Ruby | Proc | curry

概要

Proc#curry

詳細

Procをカリー化する。

カリー化を利用すると、1引数をとる高階関数複数の引数を持つ関数を渡せる。

下記の記事が非常に参考になる。
「関数型Ruby」という病(3) - カリー化(Proc#curry, Proc#flip)
http://yuroyoro.hatenablog.com/entry/2012/08/10/232443

サンプルコード

x と y を加算して文字コードを作り、 chr で文字化して
count 回数分出力する機能を カリー化します。

require 'tbpgr_utils'

_sum_to_chr_times = proc {|x, y, count| (x + y).chr * count }

bulk_puts_eval binding, <<-EOS
_sum_to_chr_times.curry[65][0][3]
_sum_to_chr_times.curry[65][1][2]
_sum_to_chr_times.curry[65][32][1]
EOS

start_from_a_curry = _sum_to_chr_times.curry[65][32]
random_counts = [*1..100].shuffle.take(10)
puts random_counts.map(&start_from_a_curry)

random_alphabet = [*(('A'.ord)..('z'.ord))].shuffle.take(10)
random_counts = [*1..100].shuffle.take(3)
random_alphabet.each do |alphabet|
  alphabet_curry = _sum_to_chr_times.curry[alphabet][0]
  puts random_counts.map(&alphabet_curry)
end

__END__
下記はTbpgrUtils gemの機能
bulk_puts_eval

https://rubygems.org/gems/tbpgr_utils
https://github.com/tbpgr/tbpgr_utils

出力

_sum_to_chr_times.curry[65][0][3]  # => "AAA"
_sum_to_chr_times.curry[65][1][2]  # => "BB"
_sum_to_chr_times.curry[65][32][1] # => "a"
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