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怠惰なRubyistへの道 - Enumerator::Lazy の使いかた
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nagachika
June 02, 2012
Technology
17
7.5k
怠惰なRubyistへの道 - Enumerator::Lazy の使いかた
みなとRuby会議01での発表「怠惰なRubyistへの道 - Enumerator::Lazy の使いかた」の発表資料を配布用に編集したものです。
nagachika
June 02, 2012
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Transcript
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&OVNFSBUPS ͬͯ·͢ 21
&OVNFSBUPS FBDIʹ͢ϒϩοΫΛอཹͨ͠ ঢ়ଶͰΦϒδΣΫτͱͯ࣋ͪ͠ճ͢ 22
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PCKUP@FOVN NFUIPEFBDI BSHT w PCKFOVN@GPS NFUIPEFBDI BSHT w &OVNFSBUPSOFX\]Z]^ ˢ͜Ε͚ͩͪΐͬͱಛघ 23
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&OVNFSBUPSOFX\]Z]^ DMBTT" EFGFBDI ZJFME ZJFMECBS ZJFME FOE FOE "OFXUP@FOVN ͱಉ͡
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4UPQ*UFSBUJPOJUFSBUJPOSFBDIFEBOFOE 27
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.FUIPE$IBJO <B C D E>NBQXJUI@JOEFYEP]TZN J] JFWFO TZNJ FOE
<B D > &OVNFSBUPS ಠࣗͷϝιου 29
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&OVNFSBUPS-B[Z ͷ৽ػೳ 33
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&OVNFSBUPS-B[ZNBQ 36
&OVNFSBUPS-B[Z > Enumerator::Lazy.instance_methods(false) map collect flat_map collect_concat select find_all reject
grep zip take take_while drop drop_wihle cycle lazy force [ruby 2.0.0dev (2012-05-30 trunk 35844)] 37
GPSDF &OVNSBUPS-B[ZGPSDF UP@BͷBMJBT Ԇ͞Ε͍ͯΔΠςϨʔλͷධՁΛ࣮ߦ 38
"-B[Z%FNP >> l = (0..5).lazy => <Enumerator::Lazy: 0..5> >> l_map
= l.map{|i| p i; i * 2 } => <Enumerator::Lazy: #<Enumerator::Lazy: 0..5>:map> # ͜ͷ࣌Ͱ·ͩϒϩοΫͷ༰࣮ߦ͞Ε͍ͯͳ͍! >> l_map.force 0 1 2 3 4 5 => [0, 2, 4, 6, 8, 10] # force ΛݺͿͱ࣮ߦ͞ΕΔ 39
&OVNFSBUPSͱͷҧ͍ .FUIPE$IBJOͷ͍͔͕ͨΑΓڧྗʹ தؒσʔλͷ੍ 40
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< > ˢNBQͷҙຯ͕ͳ͘ͳ͍ͬͯΔ 41
5SVF.FUIPE$IBJO NBQTFMFDUͱ͍ͬͨϝιου͍ͭ͘Ͱ .FUIPE$IBJOͰ͖Δɻ ͦ͏ɺ-B[ZͳΒͶɻ ͔Βͷ͏ͪҙͷܻʹΛؚΉΛฦ͢ MB[ZNBQ UP@T TFMFDU\]T] _T
^GPSDF 42
1JUGBMMPG &OVNFSBUPS NBQ TFMFDUͷΑ͏ʹϒϩοΫͷΓ Λར༻͢ΔϝιουΛ֎෦ΠςϨʔλԽ͠ ͯҙຯ͕ͳ͍ F TFMFDU
FOFYU FOFYU FOFYU FOFYU ˢTFMFDUͷҙຯ͕ͳ͘ͳ͍ͬͯΔ 43
5SVF&YUFSOBM *UFSBUPS NBQͳͲʹϒϩοΫΛͤΔͷͰ ద༻ͨ݁͠ՌΛॱʹऔΓग़ͤΔ M MB[ZTFMFDU\]J]JFWFO ^ MOFYU MOFYU
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&OVNFSBCMFWFSTJPO MBSHF@BSSBZNBQ\^TFMFDU\^ NBQ TFMFDU ($͞ΕΔ 49
&OVNFSBCMFWFSTJPO MBSHF@BSSBZNBQ\^TFMFDU\^ NBQ TFMFDU ($͞ΕΔ map ݁ՌͷͨΊ large_array ͱಉ͘͡Β͍ͷ தؒσʔλ͕ඞཁ
50
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-B[ZWFSTJPO MBSHF@BSSBZMB[ZNBQ\^TFMFDU\^GPSDF 52
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-B[ZWFSTJPO MBSHF@BSSBZMB[ZNBQ\^TFMFDU\^GPSDF 56
-B[ZWFSTJPO MBSHF@BSSBZMB[ZNBQ\^TFMFDU\^GPSDF தؒσʔλ͕ෆཁ 57
-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
1JUGBMMPG-B[Z ϝϞԽ͞Εͳ͍ GPSDFΛճݺͿͱ͏ҰFBDI͕ ݺΕΔ *0ͳͲ෭࡞༻ͷ͋ΔFBDIͩͱ݁Ռ͕ มԽ͢Δ͚Ͳ͍͍ͷ͔ͳ͊ ͍͍͔ FOVN@GPSͷΑ͏ʹFBDIͷ͔ΘΓʹͳ ΔϝιουΛࢦఆͰ͖ͳ͍ 62
-B[ZBTB#FUUFS &OVNFSBUPS -B[Z &OVNFSBUPSͷ ਖ਼౷ਐԽ൛ 63
)BQQZ-B[Z 1SPHSBNNJOH 64
0OF.PSF5IJOH IUUQTHJUIVCDPNOBHBDIJLBMB[Z@TBNQMF 65