Ruby2.7のパターンマッチングで遊んでみた.pdf

RubyKaigiで発表されていた実例を元に実際にパターンマッチで遊んでみました。
https://speakerdeck.com/k_tsj/pattern-matching-new-feature-in-ruby-2-dot-7

Transcript

1. Re:valua t ion https://fril.jp/ L ead & Delight User F irst Ownership Fail Smart 3VCZͷύλʔϯϚονϯάͰ༡ΜͰΈͨ
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    ύλʔϯϚονͷछྨ͸छྨ  ஋ͦͷ΋ͷʹϚονͤ͞Δ 7BMVF
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    ม਺ʹΞαΠϯͤ͞Δ 7BSJBCMF
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    )BTIͷܗʹϚονͤ͞Δ )BTI
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   ஋ͦͷ΋ͷʹϚονͤ͞Δ 7BMVF
   QBUUFSO ϝιου͕USVFΛฦ͢ͳΒϚον͢Δɻ
   DBTFXIFOͱ͍ͬ͠ΐɻ 1 case 0 2 in 0 3 in -1..1 4 in Integer 5 end
10. 
     
    ม਺ʹΞαΠϯͤ͞Δ 7BSJBCMF
    QBUUFSO ม਺ʹΞαΠϯͤ͞Δ͜ͱ͕Ͱ͖Δ 1 case 0 2 in a 3 p a #=> 0 4 end 1 case [0, 1] 2 in [_, _] 3 :reachable 4 end ม਺໊Λ@ʹ͢ΔͱɺϚον͸͢Δ͚Ͳ
 ΞαΠϯ͸͠ͳ͍ 1 a = 0 2 case 1 3 in ^a # means `in 0` 4 :unreachable 5 end #=> NoMatchingPatternError ͢Ͱʹଘࡏ͢Δม਺ͷ஋Λ࢖͍͍ͨ৔߹͸ɺ
 ?Λ࢖͏ &MJYJSͷQJOԋࢉࢠ
11. 
     
    ͲΕ͔ʹϚονͤ͞Δʢ"MUFSOBUJWF
    QBUUFSOʣ c 03 Ͱෳ਺ఆٛͯ͠ɺ
    ͍ͣΕ͔͕ͰUSVFΛฦͤ͹ Ϛον͢Δ 1 ['a', 1, :c].each do |value| 2 case value 3 in /a/ | 1 | Symbol 4 puts :reachable 5 end 6 end
12. 
     
    Ϛονͱม਺ʹΞαΠϯΛಉ࣌ʹߦ͏ "T
    QBUUFSO Ϛονͨ͠ม਺Λ
    ଞͷม਺ʹΞαΠϯ͢Δ
    ʜ 1 ['a', 1, :c].each do |value| 2 case value 3 in /a/ | 1 | Symbol => bbb 4 puts bbb 5 end 6 end
13. 
     
    "SSBZͷܗʹϚονͤ͞Δ "SSBZ
    QBUUFSO ࡶʹݴ͏ͱʮܗʯΛ߹ΘͤΔͱɺϚον͢Δɻ
    TQMBU Ͱ࢒Γͷม਺ΛϚονͤͨ͞Γ΋Ͱ͖Δ 1 case [0, [1, 2]] 2 in [0, [1, _] => a] 3 p a #=> [1, 2] 4 end 2 in [0, [1, _] => a] ͔͠΋ɺͦͷͱ͖
 "TύλʔϯͰ஋ͷҰ෦ΛऔΓग़ͨ͠Γɺ Ϛονͨ͠஋ΛࣺͯͨΓͰ͖Δɻ
 ʢ͜͜·ͰͷύλʔϯͷԠ༻ʣ
14. 
     
    "SSBZͷܗʹϚονͤ͞Δ "SSBZ
    QBUUFSO 1 Color = Struct.new(:red, :green, :blue) do 2 def deconstruct 3 puts '`deconstruct` is called' 4 to_a # [red, green, blue] 5 end 6 end 7 8 class Color2 < Color; end 9 10 case Color[0, 10, 0] 11 in Color2[0, a, 0] # not called because type is different 12 puts "Color2" 13 in [0, a, 0] 14 puts "Matched with array: #{a}" # => 10 15 in Color[0, a, 0] # => `deconstruct` is called 16 puts "Matched with Color: #{a}" # => 10 17 end ಺෦తʹ͸ɺEFDPOTUSVDU͕ ฦ͢"SSBZΦϒδΣΫτΛݩ ʹύλʔϯϚον͍ͤͯ͞ Δɻ
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15. 
     
    )BTIͷܗʹϚονͤ͞Δ )BTI
    QBUUFSO ࡶʹݴ͏ͱʮܗʯΛ߹ΘͤΔͱϚον͢Δɻ
    EPVCMF
    TQMBU Ͱ࢒Γͷม਺ΛϚονͤͨ͞Γ΋Ͱ͖Δ
    ͱ͍͏͜ͱ͸ɺEFDPOTUSVDUతͳԿ͔ΛΦϦδφϧΫϥε Ͱ࣮૷͢Ε͹ʜ 1 case {a: 1, b: 2, c: 3} 2 in {a: 1, b: b} 3 p "reached! b is #{b}" 4 end
16. 
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    )BTIͷܗʹϚονͤ͞Δ )BTI
    QBUUFSO 1 Person = Struct.new(:name, :age) do 2 def deconstruct_keys(keys) 3 puts "`deconstruct_keys` is called with keys #{keys}" 4 { name: name } 5 end 6 end 7 8 case Person.new('a', 30) 9 in name: # => `deconstruct_keys` is called with keys [:name] 10 p name # => 'a' 11 end ಺෦తʹ͸ɺ EFDPOTUSVDU@LFZTͷLFZʹରԠ ͢ΔLFZWBMVFΛؚΉϋογϡ ͕ฦΕ͹Ϛονͤ͞Δ͜ͱ΋Ͱ ͖Δɻ
    ͳͷͰɺಠࣗͷ1FSTPOΫϥεͷ ΦϒδΣΫτΛύλʔϯϚον ͤ͞Δ͜ͱ΋Մೳʂ
    ͍͢͝ʂ \
    OBNF
    OBNF
    ^
    ͷ4ZOUBY
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    w ಡΈࠐΈݩ
    ZBNM
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    /P42-
    w ͦ΋ͦ΋42-΍(SBQI2-ͳͲͰΫΤϦͰߜΓࠐΊΕ͹ۤ ࿑͸ͳ͍
    w Ͳ͜Β΁ΜͰ࢖͑ΔͩΖ͏
19. ื
20. 
     ͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠