怠惰なRubyistへの道 - Enumerator::Lazy の使いかた

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&OVNFSBCMF FBDIϝιου͕ఆٛ͞Εͯ ͍ΔΫϥεʹJODMVEFͯ͠ ࢖͏ .JYJO 17

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&OVNFSBCMF FBDI͚ͩ༻ҙ͓͚ͯ͠͹ NBQ TFMFDU SFKFDU HSFQ FUD ͱ͍ͬͨϝιου͕࢖͑ΔΑ͏ʹͳΔ ͜ΕΒͷϝιου͕FBDIΛ࢖ͬͯ ࣮૷͞Ε͍ͯΔ
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&OVNFSBUPS ࢖ͬͯ·͢ 21

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&OVNFSBUPS FBDIʹ౉͢ϒϩοΫΛอཹͨ͠ ঢ়ଶͰΦϒδΣΫτͱͯ࣋ͪ͠ճ͢ 22

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UP@FOVN FOVN@GPS &OVNFSBUPSͷ࡞Γ͔ͨ w &OVNFSBUPSOFX PCK NFUIPEFBDI BSHT w
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͜͜·Ͱͷ·ͱΊ w&OVNFSBUPS w0CKFDUUP@FOVN FOVN@GPS w֎෦ΠςϨʔλԽ w.FUIPE$IBJO w 32

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&OVNFSBUPS-B[Z ͷ৽ػೳ 33

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&OVNFSBUPS-B[ZNBQ 36

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&OVNFSBUPS-B[Z > Enumerator::Lazy.instance_methods(false) map collect ﬂat_map collect_concat select ﬁnd_all reject
grep zip take take_while drop drop_wihle cycle lazy force [ruby 2.0.0dev (2012-05-30 trunk 35844)] 37

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GPSDF &OVNSBUPS-B[ZGPSDF UP@BͷBMJBT ஗Ԇ͞Ε͍ͯΔΠςϨʔλͷධՁΛ࣮ߦ 38

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"-B[Z%FNP >> l = (0..5).lazy => <Enumerator::Lazy: 0..5> >> l_map
= l.map{|i| p i; i * 2 } => <Enumerator::Lazy: #<Enumerator::Lazy: 0..5>:map> # ͜ͷ࣌఺Ͱ͸·ͩϒϩοΫͷ಺༰͸࣮ߦ͞Ε͍ͯͳ͍! >> l_map.force 0 1 2 3 4 5 => [0, 2, 4, 6, 8, 10] # force ΛݺͿͱ࣮ߦ͞ΕΔ 39

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&OVNFSBUPSͱͷҧ͍ .FUIPE$IBJOͷ࢖͍͔͕ͨΑΓڧྗʹ தؒσʔλͷ཈੍ 40

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< > ˢNBQͷҙຯ͕ͳ͘ͳ͍ͬͯΔ 41

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^GPSDF 42

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-B[ZWFSTJPO MBSHF@BSSBZMB[ZNBQ\^TFMFDU\^GPSDF தؒσʔλ͕ෆཁ 57

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-B[Z$IBJO%FNP >> (0..4).lazy.select{|i| p “select:#{i}”; i.event? }.map{|i| p “map:#{i}”; i
* 2 }.force “select:0” “map:0” “select:1” “select:2” “map:2” “select:3” “select:4” “map:4” => [0, 4, 8] 58

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GPSDF < > 61

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-B[ZBTB#FUUFS &OVNFSBUPS -B[Z͸ &OVNFSBUPSͷ ਖ਼౷ਐԽ൛ 63

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怠惰なRubyistへの道 - Enumerator::Lazy の使いかた

怠惰なRubyistへの道 - Enumerator::Lazy の使いかた

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