[Ruby] Hanachan in Ruby (non-destructive array operation)

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出典: Learn You a Haskell for Great Good!

array.first

irb(main):005:0> a = [1, 2, 3]
=> [1, 2, 3]
irb(main):007:0> a.first
=> 1
irb(main):008:0> a
=> [1, 2, 3]

tail

array.drop(1)

irb(main):005:0> a = [1, 2, 3]
=> [1, 2, 3]
irb(main):009:0> a.drop(1)
=> [2, 3]
irb(main):010:0> a
=> [1, 2, 3]

init

array[0...-1]

irb(main):010:0> a
=> [1, 2, 3]
irb(main):011:0> a[0...-1]
=> [1, 2]
irb(main):012:0> a
=> [1, 2, 3]

last

array.last

irb(main):013:0> a
=> [1, 2, 3]
irb(main):014:0> a.last
=> 3
irb(main):015:0> a
=> [1, 2, 3]

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