RecordDotSyntaxのあれこれ

Transcript

1. Record Dot Syntax ͷ͋Ε͜Ε
   By lotz

   2019/12/11 ୈ2ճGHCษڧձ @ IIJ-II
   

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2. RecordDotSyntax
   https://github.com/shayne-fletcher-da/ghc-proposals/blob/record-dot-syntax/proposals/0000-record-dot-syntax.md#motivation
   

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3. RecordDotSyntaxͷجຊ
   https://github.com/shayne-fletcher-da/ghc-proposals/blob/record-dot-syntax/proposals/0000-record-dot-syntax.md#recorddotsyntax-language-extension
   

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4. RecordDotSyntaxͷ೿ੜߏจ
   https://github.com/shayne-fletcher-da/ghc-proposals/blob/record-dot-syntax/proposals/0000-record-dot-syntax.md#recorddotsyntax-language-extension
   

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5. Recordվળͷ্ʹ͋Δ
   ()$֦ு1SPQPTBM ()$7FSTJPO
   %VQMJDBUF3FDPSE'JFMET
   0WFSMPBEFE-BCFMT
   0WFSMPBEFE3FDPSE'JFMET
   "EETFU'JFMEUP)BT'JFME
   /P'JFME4FMFDUPST "DDFQUFE
   3FDPSE%PU4ZOUBY /&8
   

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6. DAMLͰͷ࣮੷͋Γ
   • DAML͸Haskell/ScalaͰ։ൃ͞Ε͍ͯΔɺ

   εϚʔτίϯτϥΫτهड़ݴޠ
   • DAMLͷ։ൃʹ͓͍ͯGHC Pluginsͱ͍͏ܗͰ
   RecordDotSyntaxͱ΄΅ಉ͡ػೳ͕࢖ΘΕ͍ͯΔ
   

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7. ఏҊͯ͠Δͷ΋DAMLͷਓ
   https://github.com/ghc-proposals/ghc-proposals/pull/282
   

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8. PR΁ͷ൓Ԡ
   https://github.com/ghc-proposals/ghc-proposals/pull/282#issuecomment-540968106
   *TUSPOHMZTVQQPSUUIFEJSFDUJPOPG
   USBWFMPGUIJTQSPQPTBM
   

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9. PR΁ͷ൓Ԡ
   5IFMPTTPGQPMZNPSQIJDVQEBUFJT
   BIVHFQSPCMFN JNP
   https://github.com/ghc-proposals/ghc-proposals/pull/282#issuecomment-541111003
   

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10. PR΁ͷ൓Ԡ
    5IJTQSPQPTBMJTGVMMPGVUUFSOPOTFOTF
    https://github.com/ghc-proposals/ghc-proposals/pull/282#issuecomment-541460439
    

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11. > :t (.age)
    (.age) :: Person -> Int
    > :t (. age)
    (. age) :: (Int -> c) -> Person -> c
    ۭനͷ༗Γແ͠Ͱ͜͜·Ͱҙຯ͕มΘΔͷ͸
    ॳ৺ऀʹ͸೉͘͠ͳ͍ʁ
    

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12. ࠓͷεςʔλε
    https://github.com/ghc-proposals/ghc-proposals/pull/282#issuecomment-559259994
    8JUIUIFUIDPNNFOU BGUFSSFBDUJPOTPOUIFJOJUJBM
    QPTU QBSUJDJQBOUTBOEBUMFBTUQPMMTPGVTFSTFOUJNFOU
    *EMJLFUPUVSOUIJTPWFSUPUIFDPNNJUUFF
    

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13. ະղܾ໰୊
    https://twitter.com/ndm_haskell/status/1190680324495302658
    

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14. ͋Ε͜Ε
    

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15. f a.b.c x ͷύʔε
    f a.foo.bar.baz.quux 12
    ͸
    f (a.foo.bar.baz.quux) 12
    ͱධՁ͞ΕΔ
    ((f a).foo.bar.baz.quux) 12Ͱ͸ͳ͍
    https://github.com/shayne-fletcher-da/ghc-proposals/blob/record-dot-syntax/proposals/0000-record-dot-syntax.md#record-selection
    

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16. Lens͸ʁ
    • f $ record ^. field ͕ f record.field ͱॻ͚Δ
    • Lens͸ෳࡶա͗Δ…
    • Lensͱ͸໊લۭ͕ؒҟͳΔͷͰҰॹʹ࢖͑Δ
    https://github.com/shayne-fletcher-da/ghc-proposals/blob/record-dot-syntax/proposals/0000-record-dot-syntax.md#alternatives-to-this-proposal
    

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17. ͜͏͍͏දه͸ແ͍
    • ߋ৽ʹؔ͢Δߏจ
    • a{field * 2}
    • a{field <- (*2)}
    • a{field * = 2}
    • ߋ৽ʹؔ͢ΔηΫγϣϯ
    • ({a=})
    • ({a=b})
    • (.lbl=)
    https://github.com/shayne-fletcher-da/ghc-proposals/blob/record-dot-syntax/proposals/0000-record-dot-syntax.md#alternatives-within-this-proposal
    

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18. Ҏ্
    

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