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Goに無名関数の糖衣構文いれたらどうなるの? / Considering the introduction of the anonymous function syntax sugar into Go

yuroyoro
October 28, 2019

Goに無名関数の糖衣構文いれたらどうなるの? / Considering the introduction of the anonymous function syntax sugar into Go

GoCon 2019 LT

yuroyoro

October 28, 2019
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  1. Considering the introduction of the anonymous function syntax sugar into

    Go !ZVSPZPSP (Pʹແ໊ؔ਺ͷ౶ҥߏจ͍ΕͨΒͲ͏ͳΔͷʁ
  2. ಈతܕ෇͖ͳݴޠͰ͸ʁ const f = (x) => { return x *

    2 } +BWB4DSJQU 1ZUIPO f = lambda x: x * 2 3VCZ f = ->(x) { x * 2 }
  3. ੩తܕ෇͖ͳݴޠͰ͸ʁ const f = (x:number): number => { return x

    * 2 } 5ZQF4DSJQU +BWB 4DBMB Function<Integer, Integer> f = (Integer x) -> { return x * 2; }; val f: (Int) => Int = (x) => { x * 2 }
  4. ͷ࣍ʹ໊લ͕དྷͨΒɺࣜ &YQS ʹܾ·Δ var f = ( x * 2

    ) ↑ current: ( : _Lparen next : x : _Name Expr
  5. "SSPX'VODUJPO͕ೖΔͱʜʜ var f = ( x int ) int =>

    { … } ↑ current: ( : _Lparen next : x : _Name
  6. ͷ࣍ʹ໊લ͕དྷͯ΋ɺࣜ &YQS ͔ؔ਺ 'VOD5ZQF ͔ Θ͔Βͳ͍ var f = (

    x int ) int => { … } ↑ current: ( : _Lparen next : x : _Name Expr or FuncType?
  7. AGVODAΛAAʹม͑Δ͚ͩ ->(x int) int => { return x * 2

    } func(x int) int => { return x * 2 } ↓
  8. ॻ͍ͯΈͨ src/cmd/compile/internal/syntax/parser.go | 2 +- src/cmd/compile/internal/syntax/scanner.go | 7 ++++++- src/cmd/compile/internal/syntax/token_string.go

    | 4 ++-- src/cmd/compile/internal/syntax/tokens.go | 1 + 4 files changed, 10 insertions(+), 4 deletions(-)
  9. %FNP package main import "fmt" func main() { f :=

    ->(x int, y int) int { return x + y } fmt.Printf("%d\n", f(3, 4)) fmt.Printf("%d", higherFunc(f)) } func higherFunc(f ->(x int, y int) int) int { return f(1, 2) }
  10. ͨͱ͑͹ɺ+BWBͰ͸Ҿ਺ͷܕએݴΛ লུͰ͖Δ ↓ +BWB Function<Integer, Integer> f = (Integer x)

    -> { return x * 2; }; Function<Integer, Integer> f = (x) -> { return x * 2; };
  11. 4DBMBͰ͸ฦΓ஋ܕΛਪ࿦ͯ͘͠ΕΔ ↓ 4DBMB val f: Int => Int = (x:

    Int) => { x * 2 } val f = (x: Int) => { x * 2 }
  12. SFUVSOΛলུͰ͖Δݴޠ΋ଟ͍ ↓ +BWB Function<Integer, Integer> f = (x) -> {

    return x * 2; }; Function<Integer, Integer> f = (x) -> { x * 2; };
  13. ؔ਺͕࢖ΘΕΔ৔ॴͷܕ͕Θ͔͍ͬͯΔ৔߹͸ ؔ਺ࣗମͷҾ਺΍ฦΓ஋ΛলུͰ͖Δ 4DBMB val arr = Array(1, 2) // Array<Int>#mapͷҾ਺͸

    // (Int) => AͳͷͰҾ਺͕Intͱਪ࿦ɺ // ؔ਺ຊମ͔ΒฦΓ஋͕Intͱਪ࿦ arr.map((x) => { x * 2 })