Functional TypeScript

オープンデベロッパーズカンファレンス(ODC)2024 での発表資料

1. 5ZQF4DSJQU
   ͱؔ਺ܕϓϩάϥϛϯά  גࣜձࣾ Ұٳ ҏ౻ ௚໵
2. ઌʹ૯࿦ • ؔ਺ܕϓϩάϥϛϯάͷΤοηϯεΛऔΓೖΕΔ͜ͱͰΑΓྑ͍ϓϩάϥϛϯά͕Ͱ͖Δݴޠ – 3FBDU
   ͳͲ͕ྑ͍ྫ – ߴػೳͳܕγεςϜɺؔ਺Ϧςϥϧɺߴ֊ؔ਺ɺΫϩʔδϟɺNBQ
   
   SFEVDFɺ෼ׂ୅ೖͳͲͷγϯλοΫεαϙʔτ – ୅਺తσʔλܕ΋ΤϛϡϨʔτ͸Ͱ͖Δ • )BTLFMM
   ΍ 4DBMB
   ͷΑ͏ͳؔ਺ܕϓϩάϥϛϯάݴޠʹൺֱ͢Δͱػೳ͸ෆ଍͍ͯ͠Δ – ͦΕ͕ࠓޙɺվྑ͞Ε͍ͯ͘ϩʔυϚοϓ͸ߟ͑ʹ͍͘ • ྫ֎΍ΤϥʔΛؚΉ෭࡞༻ΛͲ͏ѻ͏͔ɺӬଓσʔλΛͲ͏ѻ͏͔͸ݴޠ͕ࢦࣔͯ͘͠Εͳ͍ – )BTLFMM
   ΍ 4DBMBɺ'
   ͳͲͱಉ༷ͷΞϓϩʔνΛͱΖ͏ʹ΋ɺݴޠͷαϙʔτػߏ͕ෆे෼ – αʔυύʔςΟϥΠϒϥϦͰʮิ͏ʯఔ౓͕ݶ౓͔
3. ͦ΋ͦ΋ʮؔ਺ܕϓϩάϥϛϯάʯͬͯ • ໋ྩܕ 
   ؔ਺ܕ – จ ໭Γ஋Λ൐Θͳ͍
   ͰܭࢉΛߏ੒͢Δ uuu ໋ྩܕ – ࣜ ໭Γ஋Λ൐͏
   ͰܭࢉΛએݴ͢Δ uuu ؔ਺ܕ • ؔ਺ܕϓϩάϥϛϯάͬΆ͍ΠσΟΦϜ – NBQ
   
   SFEVDF – ෦෼ద༻ɺΧϦʔԽ • ܕγεςϜ – ୅਺తσʔλܕͱύλʔϯϚον – จ຺෇͖ܭࢉɺϞφυɺܕΫϥεɺߴ֊ଟ૬uuu • Πϛϡʔλϒϧ 
   ϛϡʔλϒϧ – Ӭଓσʔλ
4. ໋ྩܕ
   GPS
   จͰॻ͘ int total = 0; for (int i = 1; i <= n; i++) { total += i; } • GPSจͱ୅ೖจͰɺ܁Γฦ͠ԋࢉ݁ՌΛॻ͖ࠐΉ ୅ೖ͢Δ
   ໋ྩΛߦ͍ͬͯΔ • ܭࢉػ΁ͷ໋ྩ uuu
   ໋ྩܕ • จͰܭࢉΛߏ੒͢Δͱɺ໋ྩతʹͳΔ
5. ؔ਺ܕ
   ࠶ؼతʹؔ਺Λద༻͢Δ • ࣜʹΑΓܭࢉΛએݴ͢Δ • ࣜ͸ඞͣ஋Λ໭͢ɻͦͷ஋ʹ࠶ͼؔ਺Λద༻͢Δ • ࣜͰܭࢉΛߏ੒͢ΔͱɺએݴతʹͳΔ let s = foldl (+) 0 [1 .. n] )BTLFMM let s = [1, 2, 3, 4, 5].reduce((acc, i) => acc + i, 0)``` let s = [1, 2, 3, 4, 5].reduce((acc, i) => acc + i, 0) 5ZQF4DSJQU
6. ؔ਺ʹΑΔΦϒδΣΫτͷঢ়ଶભҠ ͋Δঢ়ଶ T
   ʹؔ਺ G
   Λద༻ͯ͠ɺผͷঢ়ଶ T
   ΛಘΔ // 顧客をアーカイブ状態にする export const archiveCustomer = (customer: Customer): Customer => ({ ...customer, archived: true, })) 5ZQF4DSJQU 𝑠 𝑠′ 𝑓
7. customer.archive() 5ZQF4DSJQU const archived = archiveCustomer(customer) 5ZQF4DSJQU • ໋ྩతʹॻ͘ – ΦϒδΣΫτͷ಺෦ঢ়ଶΛॻ͖׵͑Δ໋ྩΛߦ͏͜ͱͰɺঢ়ଶΛมԽͤ͞Δ – ঢ়ଶͷมԽ͕҉໧త • ؔ਺త એݴత
   ʹॻ͘ – Ҿ਺ͷΦϒδΣΫτʹؔ਺Λద༻ͯ͠ɺঢ়ଶભҠޙͷΦϒδΣΫτΛಘΔ – ભҠલͷঢ়ଶ͸ඞͣҾ਺ʹݱΕɺભҠޙͷঢ়ଶ͸໭Γ஋ʹݱΕΔ
8. 𝑓 ͱ͋Δू߹4 ·ͨଞͷू߹4 ͋Δू߹ʹଐ͢Δ஋Λɺؔ਺ G
   ʹΑΓɺ·ͨଞͷू߹ʹଐ͢Δ஋ʹࣸ͢ ͜Ε͕ͲΜͳू߹͔هड़͢Δͷ͕ʮܕʯ
9. એݴతʹؔ਺Λهड़͢Δͷ͸΍Γ΍͍͢ݴޠ • ୈҰڃؔ਺ɺߴ֊ؔ਺ɺΫϩʔδϟ • ؔ਺Ϧςϥϧ • ෼ׂ୅ೖ • NBQ
   
   SFEVDF • ੩తܕ෇͚ɺܕਪ࿦ ʮࣜͰܭࢉΛએݴతʹఆٛ͢Δʯͱ͍͏఺ʹ͓͍ͯ͸े෼ͳػೳΛ༗͢Δ ෼ׂ୅ೖͷγϯλοΫεͰΠϛϡʔλϒϧͳؔ਺΋هड़͠΍͍͢
10. ΧϦʔԽ͸ݴޠͷػೳͱͯ͠͸ͳ͍͕ɺࣗ෼Ͱهड़͢Ε͹ྑ͍ • ΫϩʔδϟΛฦؔ͢਺ͱͯ͠ఆٛ͢Ε͹Α͍ • ෦෼ద༻ʹΑΔ %FQFOEFODZ
    *OKFDUJPO ͳͲʹ΋ॏཁ export type getTagSortOrder = ({ groupId }: { groupId: RestaurantGroupId }) => ResultAsync<number, PrismaClientError> export const getTagSortOrder = ({ prisma }: applicationContext): getTagSortOrder => ({ groupId }) => ResultAsync.fromPromise( prisma.tag .aggregate({ _max: { sortOrder: true, }, where: { groupId }, }) .then((x) => (x._max.sortOrder ? x._max.sortOrder + 1 : 1)), PrismaClientError )
11. 5ZQF4DSJQU
    ͷܕγεςϜ • ߏ଄త෦෼ܕ TUSVDUVSBM
    TVCZQF
    ͰߴػೳͳܕγεςϜɾܕਪ࿦ – Ϧςϥϧܕ – δΣωϦΫε – ߹ซܕ 6OJPO
    
    ަࠩܕ *OUFSTFDUJPO – ಈతͳܕఆٛ uuu $POEJUJPJOBM
    5ZQFTɺ6UJMJUZ
    5ZQFTɺ.BQQFE
    5ZQFTɺJOGFS
     • ҎԼ͸ɺΤϛϡϨʔτͰ͖Δ – ୅਺తσʔλܕͱύλʔϯϚον • Ͱ͸͋Δ͕ɺҎԼ͸ͳ͍ – 0QUJPOBM
    ΍ 3FTVMU
    ͳͲΛந৅తʹѻ͏࢓૊Έ uuu Ϟφυ΍ܕΫϥεɺߴ֊ଟ૬ FUD
12. ୅਺తσʔλܕ uuu ੩తܕ෇͚ͷؔ਺ܕݴޠͰσʔλߏ଄Λఆٛ͢Δखஈ • )BTLFMM
    ͳͲͷݴޠͰ͸σʔλߏ଄Λఆٛ͢Δͷʹ୅਺తσʔλܕͰදݱ͢Δ • ܕΛ૊Έ߹ΘͤΔͷʹੵ "/%
    ͚ͩͰͳ͘ ࿨ 03
    ͕࢖͑Δ data Bool = True | False data Maybe a = Nothing | Just a )BTLFMM )BTLFMM data UnionFind = UnionFind { parent :: IM.IntMap Int, size :: IM.IntMap Int } )BTLFMM
13. ࿨Ͱ૊Έ߹Θͤͯߏஙͨ͠΋ͷ͸ɺύλʔϯϚονͰ෼ղ main = do let someValue :: Maybe String someValue = ... case someValue of Just s -> putStrLn (s ++ ", naoya") Nothing -> putStrLn "Farewell" data Maybe a = Nothing | Just a )BTLFMM )BTLFMM +VTU
    4USJOH
    ͔ /PUIJOH
    ͷͲͪΒ͔ .BZCF
    ܕΛύλʔϯϚονͰ෼ղ͢Δ
14. 5ZQF4DSJQU
    ͸૊ΈࠐΈͰ͸୅਺తσʔλܕΛαϙʔτͯ͠ͳ͍͕ɺΤϛϡϨʔτͰ͖Δ interface Empty { kind: "Empty" } interface Cons<T> { kind: "Cons" head: T tail: List<T> } export type List<T> = Empty | Cons<T> data List a = Empty | Cons a (List a) 5ZQF4DSJQU )BTLFMM ϦςϥϧܕͰλάΛ͚͓ͭͯ͘ ϢχΦϯͰ૊Έ߹Θͤͨܕ
15. // List<T> への map 関数を実装 type map = <T, U>(f: (a: T) => U, xs: List<T>) => List<U> export const map: map = (f, xs) => { switch (xs.kind) { case "Empty": return Empty() case "Cons": return Cons(f(xs.head), map(f, xs.tail)) default: assertNever(xs) } } export function assertNever(_: never): never { throw new Error() } console.log(map(i => i * 2, myList)) 5ZQF4DSJQU λάʹԠͯ͡෼ղ ϦςϥϧܕͳͷͰͪΌΜͱܕ͕ޮ͘ ͜ΕΛೖΕΔ͜ͱͰ໢ཏੑνΣοΫ͕ޮ͘
16. ͜͜·ͰݟΔͱؔ਺ܕελΠϧͰ΍͍ͬͯ͘ͷʹे෼ʹݟ͑Δ • એݴతΠσΟΦϜ͸ॻ͖΍͍͢ • ෼ׂ୅ೖͰΠϛϡʔλϒϧʹσʔλߋ৽͢Δͷ΋΍Γ΍͍͢ • ߴػೳͳܕγεςϜ • ΧϦʔԽ΍୅਺తσʔλܕͬΆ͍͜ͱ΋Ͱ͖Δ
17. ଍Γͳ͍ͱࢥ͍ͬͯΔ఺ ओ؍ • 0QUJPOBMɺ3FTVMU ͳͲʮจ຺෇͖ܭࢉʯͷͨΊͷܕ͕ͳ͍ɻ·ͨͦΕΛѻ͏ࢧԉػߏ͕ͳ͍ • Ӭଓσʔλߏ଄͕جຊʹ͸ͳ͍ͬͯͳ͍ ۀ຿ΞϓϦέʔγϣϯࢹ఺Ͱ͸จ຺ ෇͖ܭࢉʹର͢Δػߏ͕ͳ͍ͷ͕ɺ ࠷΋೰·͍͠
18. export function toColor(value: string): Result<Color, ValidationError> { return /^#[0-9a-f]{3}([0-9a-f]{3})?$/i.test(value) ? ok(value as Color) : err(new ValidationError('⾊の値が不正です。#FFFFFF形式で指定してください')) } 5ZQF4DSJQU 3FTVMU
    ܕ uuu
    ੒ޭ 
    ࣦഊͷ෼ذΛܕͰදݱͰ͖Δ OFWFSUISPXɺGQUTɺ&GGFDU
    ͳͲ͕ಉ༷ͷܕΛϥΠϒϥϦͰఏڙ͢Δ
19. 3FTVMUܕͰɺࣦഊͷՄೳੑͷ͋ΔܭࢉΛҰຊಓʹ߹੒͢Δ͜ͱ͕Ͱ͖Δ import { Result, ok, err } from 'neverthrow' function itsUnder100(n: number): Result<number, Error> { return n <= 100 ? ok(n) : err(new Error('100より大きい数字です')) } function itsEven(n: number): Result<number, Error> { return n % 2 == 0 ? ok(n) : err(new Error('奇数です')) } function itsPositive(n: number): Result<number, Error> { return n > 0 ? ok(n) : err(new Error('負数です')) } const result = ok(96).andThen(itsUnder100).andThen(itsEven).andThen(itsPositive) result.match( (n) => console.log(n), (error) => { throw error } )
20. ͔͠͠ɺ3FTVMU
    ܕʹೖͬͨ஋͕ೖΕࢠʹͳΔͱ΍΍͍͜͠ export const Tag = (input: TagInput): Result<Tag, ValidationError> => { const tagId = TagId(input.id) const groupId = RestaurantGroupId(input.groupId) const label = TagLabel(input.label) const icon = input.icon && input.iconType ? TagIcon({ symbol: input.icon, type: input.iconType, color: input.color, }) : ok(NoIcon()) const sortOrder = FractionalIndex(input.sortOrder) const values = Result.combine(tuple(tagId, groupId, label, icon, sortOrder)) return values.map(([id, groupId, label, icon, sortOrder]) => ({ ...input, id, groupId, label, icon, sortOrder, })) } ஋͕͍͍ͩͨ
    3FTVMU
    ʹೖ͍ͬͯΔ ͨΊɺෳ਺
    3FTVMU
    ͕͋Δͱ߹੒͠ ͯϑϥοτʹ͢Δඞཁ͕͋Γ໘౗ ͳ࡞ۀʹͳͬͯ͘Δ
21. ʮίϯςφʹೖͬͨจ຺͖ͭͷ஋ʯΛѻ͏ɺ૊ΈࠐΈͷػೳ͕͋ΔݴޠͳΒuuu ͜ͷखͷػߏ͕͋Ε͹ೝ஌ෛՙ௿࣮͘૷Ͱ͖Δ͕ɺ࢒೦ͳ͕Β 5ZQF4DSJQU
    ʹ͸ͳ͍ GQUT
    ΍ &GGFDU
    ͕ϑϥοτ߹੒ͷؔ਺ QJQF
    Λఏڙͯ͠͸͍Δ͕ɺॻ͖ຯ͸ྑ͘ͳ͍ makeTagId :: String -> Either ValidationError TagId makeTagId tagId | null tagId = Left (ValidationError "tagId is empty") | otherwise = Right (TagId tagId) makeTag :: String -> String -> Int -> Either ValidationError Tag makeTag id gid order = do tagId <- makeTagId id groupId <- makeGroupId gid sortOrder <- makeSortOder order return (Tag tagId groupId sortOrder) )BTLFMM ྫ͑͹Ϟφυʹ͸ɺೖΕࢠʹ ͳͬͨίʔυΛฏୱԽ͢Δޮ༻ ͕͋Δ
22. ӬଓσʔλϓϩάϥϛϯάɺӬଓσʔλߏ଄ ʦೖ໳ʧؔ਺ϓϩάϥϛϯάʕ࣭ͷߴ͍ίʔυΛ͢͹΍͘௚ײతʹॻ͚Δʂ IUUQTHJIZPKQEFWGFBUVSFGVODUJPOBMQSPH
23. Ӭଓσʔλߏ଄ • มߋ͞ΕΔࡍʹมߋલͷόʔδϣϯΛৗʹอ࣋͢Δσʔλߏ଄ • 4USVDUVSBM
    4IBSJOH
    ʹΑΓɺޮ཰తʹͦΕΒͷσʔλΛอ࣋͢Δ • Πϛϡʔλϒϧʹσʔλߏ଄Λมߋ͢Δͱ͖ɺશମΛίϐʔ͠ͳͯ͘ࡁΉ https://vimeo.com/166790294
24. )BTLFMM
    ͷجຊతͳσʔλߏ଄͸Ӭଓσʔλߏ଄ main :: IO () main = do let xs = scanl' (flip Set.insert) Set.empty [1 .. 10 ^ 5] print $ Set.size (last xs) )BTLFMM Ӭଓσʔλߏ଄ͳΒΠϛϡʔλϒϧʹσʔλΛѻ͍ͭͭύϑΥʔϚϯεͱཱ྆Ͱ͖Δ 
    ݸͷ 4FU
    ͕࡞ΒΕΔ͕ͦͷ౎ ౓શମ͕ຖճίϐʔ͞ΕΔΘ͚Ͱ ͸ͳ͍
25. 5ZQF4DSJQU
    ͱӬଓσʔλߏ଄ • ૊ΈࠐΈͷσʔλߏ଄͸Ӭଓσʔλߏ଄Ͱ͸ͳ͘ɺجຊ͸ϛϡʔλϒϧ • *NNVUBCMFKT
    ͳͲӬଓσʔλߏ଄Λఏڙ͢ΔϥΠϒϥϦ͕͋Δ͕ɺ͍·͍ͪྲྀߦͬͯͳ͍ – ۀ຿ΞϓϦέʔγϣͰ͸Ӭଓσʔλߏ଄Λ࢖͏ඞཁͷ͋Δ΄ͲɺύϑΥʔϚϯεཁ͕݅ݫ͍͠৔໘͕গͳ͍
26. ࠶ܝ
    ૯࿦ • ؔ਺ܕϓϩάϥϛϯάͷΤοηϯεΛऔΓೖΕΔ͜ͱͰΑΓྑ͍ϓϩάϥϛϯά͕Ͱ͖Δݴޠ – 3FBDU
    ͳͲ͕ྑ͍ྫ – ߴػೳͳܕγεςϜɺؔ਺Ϧςϥϧɺߴ֊ؔ਺ɺΫϩʔδϟɺNBQ
    
    SFEVDFɺ෼ׂ୅ೖͳͲͷγϯλοΫεαϙʔτ – ୅਺తσʔλܕ΋ΤϛϡϨʔτ͸Ͱ͖Δ • )BTLFMM
    ΍ 4DBMB
    ͷΑ͏ͳؔ਺ܕϓϩάϥϛϯάݴޠʹൺֱ͢Δͱػೳ͸ෆ଍͍ͯ͠Δ – ͦΕ͕ࠓޙɺվྑ͞Ε͍ͯ͘ϩʔυϚοϓ͸ߟ͑ʹ͍͘ • ྫ֎΍ΤϥʔΛؚΉ෭࡞༻ΛͲ͏ѻ͏͔ɺӬଓσʔλΛͲ͏ѻ͏͔͸ݴޠ͕ࢦࣔͯ͘͠Εͳ͍ – )BTLFMM
    ΍ 4DBMBɺ'
    ͳͲͱಉ༷ͷΞϓϩʔνΛͱΖ͏ʹ΋ɺݴޠͷαϙʔτػߏ͕ෆे෼ – αʔυύʔςΟϥΠϒϥϦͰʮิ͏ʯఔ౓͕ݶ౓͔
27. ࢲݟ • 5ZQF4DSJQU
    ͸ؔ਺ܕϓϩάϥϛϯάʹಛԽͨ͠ݴޠͰ͸ͳ͍ͨΊɺؔ਺ܕʹدͤ͗͢Δͷ΋ߟ͑΋ͷ – खଓ͖తʹॻ͚͹Α͍ͱ͜Ζ͸ɺखଓ͖Λ࢖͏ – ಛʹ *0
    ΍ඇಉظॲཧपΓ͸ແཧʹؔ਺ܕʹ͢Δඞཁ͸ͳ͍ • )BTLFMM
    ͳͲଞͷؔ਺ܕݴޠͰ΋ɺ࡞༻Λ൐͏ͱ͜Ζ͸खଓ͖తʹ࣮૷͢Δ͜ͱ΋ଟ͍ – ࢀߟʰ5ZQF4DSJQUͰͲ͜·Ͱʮؔ਺ܕϓϩάϥϛϯάʯ͢Δ͔ ᴷ
    ʮखଓ͖ )BTLFMMʯ͔Βߟ࡯͢Δʱ • IUUQTVTFSGJSTUJLZVDPKQFOUSZ • *0
    ෼཭Λੵۃతʹߦͬͯۀ຿ϩδοΫΛ७ਮʹ͠ɺ७ਮؔ਺Ͱߏ੒͢Δͷ͸ྑ͍ϓϥΫςΟεͩͱࢥ͏