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,PUMJO'FTU:VUB5BLBOBTIJ
ωετͨ͠EBUBDMBTTͷ໘ͳߋ৽ʹ͞Α͏ͳΒʂ
-FOTΛ࡞ͬͯཧղ͢Δ"SSPXͷ0QUJDTͷੈք
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ࣗݾհ
w:VUB5BLBOBTIJ
w 9!TIJJUB@
w-*/&Ϡϑʔגࣜձࣾ-*/&ͷ"OESPJEΞϓϦ։ൃ
w͖ͳ,PUMJOͷݴޠػೳεϚʔτΩϟετͱ$POUSBDU
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ൃද༰
wෳࡶͳEBUBDMBTTมߋͷਏ͞ͱ-FOTʹΑΔղܾ
w-FOTΛࣗ࡞ͯ͠ΈΛཧղ
w-FOTΛศརʹѻ͏ϥΠϒϥϦ
w-FOTͷݶքͱ0QUJDT
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ෳࡶͳEBUBDMBTTมߋͷਏ͞
data class User(val id: Int, val profile: Profile)
data class Profile(val name: String, val statusMessage: StatusMessage)
data class StatusMessage(val text: String, val updatedTime: Long)
fun capitalizeStatusMessage(user: User): User = user.copy(
profile = user.profile.copy(
statusMessage = user.profile.statusMessage.copy(
text = user.profile.statusMessage.text.uppercase()
)
)
)
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-FOTʹΑΔਏ͞ͷܰݮ
fun capitalizeStatusMessage(user: User): User = user.copy(
profile = user.profile.copy(
statusMessage = user.profile.statusMessage.copy(
text = user.profile.statusMessage.text.uppercase()
)
)
)
fun capitalizeStatusMessageWithLens(user: User): User =
User.profile.statusMessage.text.modify(user) { it.uppercase() }
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-FOTͱʁ
wؔܕϓϩάϥϛϯάͰɺෆมσʔλͷૢ࡞ʹ༻͍ΒΕΔ
w,PUMJOͰ"SSPXLUϥΠϒϥϦͰར༻Մೳ
w(FUUFSͱ4FUUFSͷϖΞͰߏ͞Ε͍ͯΔ
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-FOTΛ͏
//
Get
fun getStatusMessage(user: User): String =
User.profile.statusMessage.text.get(user)
//
Set
fun updateStatusMessage(user: User, newMessage: String): User =
User.profile.statusMessage.text.set(user, newMessage)
//
Modify(Getter + Setter)
fun capitalizeStatusMessage(user: User): User =
User.profile.statusMessage.text.modify(user) { it.uppercase() }
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-FOTͷΈΛཧղ͢Δ
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-FOTͷΈΛཧղ͢Δ
interface PLens : POptional {
fun get(source: S): A
override fun set(source: S, focus: B): T
. .
.
}
w"SSPXLUͰͷ-FOTͷ࣮
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-FOTͷΈΛ࡞ͬͯཧղ͢Δ
(FUUFSͷ࡞
4FUUFSͷ࡞
(FUUFSͱ4FUUFSΛΈ߹Θͤͯ-FOTΛ࡞Δ
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(FUUFSͷ࣮ํ
wHFU
ؔΛ༻ҙ
w൚༻తʹ͑Δ༷ʹδΣωϦΫεΛར༻
wEBUBDMBTTਂ͍ॴʹର͢ΔHFUUFS؆୯ʹऔಘՄೳʹ͢Δ
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(FUUFSͷ࡞
fun interface Getter {
fun get(source: S): A
}
data class User(val id: Int, val profile: Profile)
fun getProfile(user: User): Profile {
val profileGetter = Getter { source
->
source.profile }
return profileGetter.get(user)
}
w4(FUUFSͷιʔεͷܕ 6TFS
w"(FUUFSͷϑΥʔΧεͷܕ 1SP
fi
MF
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(FUUFSͷ߹
fun interface Getter {
fun get(source: S): A
operator fun plus(other: Getter): Getter = TODO()
}
data class User(val id: Int, val profile: Profile)
data class Profile(val name: String, val statusMessage: StatusMessage)
fun getStatusMessage(user: User): StatusMessage {
val profileGetter = Getter { source
->
source.profile }
val statusMessageGetter = Getter
{ source
- >
source.statusMessage }
val composedGetter: Getter = profileGetter + statusMessageGetter
return composedGetter.get(user)
}
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(FUUFSͷ߹
fun interface Getter {
fun get(source: S): A
operator fun plus(other: Getter): Getter =
Getter { source: S
->
val a: A = get(source)
other.get(a)
}
}
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4FUUFSͷ࡞
fun interface Setter {
fun modify(source: S, map: (A)
->
A): S
fun set(source: S, focus: A): S = modify(source) { _: A
->
focus }
}
data class User(val id: Int, val profile: Profile)
fun setProfile(user: User, newProfile: Profile): User {
val profileSetter = Setter { source, map
->
val modifiedProfile = map(source.profile)
source.copy(profile = modifiedProfile)
}
return profileSetter.set(user, newProfile)
}
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4FUUFSͷ߹
fun interface Setter {
fun modify(source: S, map: (A)
->
A): S
fun set(source: S, focus: A): S = modify(source) { _: A
->
focus }
operator fun plus(other: Setter): Setter =
Setter { source: S, map: (B)
->
B
->
modify(source) { focus: A
-
>
other.modify(focus, map) }
}
}
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4FUUFSͷ߹
data class User(val id: Int, val profile: Profile)
data class Profile(val name: String, val statusMessage: StatusMessage)
fun setStatusMessage(user: User, newStatusMessage: StatusMessage): User {
val profileSetter = Setter { source, map
->
val modifiedProfile = map(source.profile)
source.copy(profile = modifiedProfile)
}
val statusMessageSetter = Setter { source, map
->
val modifiedStatusMessage = map(source.statusMessage)
source.copy(statusMessage = modifiedStatusMessage)
}
val composedSetter: Setter =
profileSetter + statusMessageSetter
return composedSetter.set(user, newStatusMessage)
}
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-FOTͷ࡞
class Lens(
private val getter: Getter,
private val setter: Setter
) : Getter by getter, Setter by setter {
operator fun plus(other: Lens): Lens = Lens(
getter = this.getter + other.getter,
setter = this.setter + other.setter
)
}
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࡞ͨ͠-FOTͷར༻
data class User(val id: Int, val profile: Profile)
data class Profile(val name: String, val statusMessage: StatusMessage)
data class StatusMessage(val text: String, val updatedTime: Long)
fun createStatusMessageTextLens(): Lens {
val profileLens = Lens(
getter = { source
->
source.profile },
setter = { source, map
->
source.copy(profile = map(source.profile)) }
)
val statusMessageLens = Lens(
getter = { source
->
source.statusMessage },
setter = { source, map
->
source.copy(statusMessage = map(source.statusMessage)) }
)
val textLens = Lens(
getter = { source
->
source.text },
setter = { source, map
->
source.copy(text = map(source.text)) }
)
return profileLens + statusMessageLens + textLens
}
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࡞ͨ͠-FOTͷར༻
data class User(val id: Int, val profile: Profile)
data class Profile(val name: String, val statusMessage: StatusMessage)
data class StatusMessage(val text: String, val updatedTime: Long)
fun createStatusMessageTextLens(): Lens { … }
fun myLens(user: User, newMessage: String) {
val lens = createStatusMessageTextLens()
val text: String = lens.get(user)
val newUser1: User = lens.set(user, newMessage)
val newUser2: User = lens.modify(user) { it.uppercase() }
}
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࡞ͨ͠-FOTͷܽ
fun createStatusMessageTextLens(): Lens {
val profileLens = Lens(
getter = { source
->
source.profile },
setter = { source, map
->
source.copy(profile = map(source.profile)) }
)
val statusMessageLens = Lens(
getter = { source
->
source.statusMessage },
setter = { source, map
->
source.copy(statusMessage = map(source.statusMessage)) }
)
val textLens = Lens(
getter = { source
->
source.text },
setter = { source, map
->
source.copy(text = map(source.text)) }
)
return profileLens + statusMessageLens + textLens
}
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࡞ͨ͠-FOTͷܽ
fun createStatusMessageTextLens(): Lens {
val profileLens = Lens(
getter = { source
->
source.profile },
setter = { source, map
->
source.copy(profile = map(source.profile)) }
)
val statusMessageLens = Lens(
getter = { source
->
source.statusMessage },
setter = { source, map
->
source.copy(statusMessage = map(source.statusMessage)) }
)
val textLens = Lens(
getter = { source
->
source.text },
setter = { source, map
->
source.copy(text = map(source.text)) }
)
return profileLens + statusMessageLens + textLens
}
fun createStatusMessageTextLensByArrow(): Lens =
User.profile.statusMessage.text
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"SSPXLUͷ-FOTͷར༻ํ๏
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"SSPXLUͷ-FOTͷར༻ํ๏
w-FOTͷͨΊͷίʔυੜํ๏
w-FOTΛΑΓศརʹ׆༻
w ϢʔςΟϦςΟؔ
w ଞϥΠϒϥϦͱͷ࿈ܞ
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-FOTͷͨΊͷίʔυੜ
@optics
data class Profile(val name: String, val statusMessage: StatusMessage) {
companion object
}
w!PQUJDTΛEBUBDMBTTʹ͚ͭΔ
wۭͷDPNQBOJPOPCKFDUΛఆٛ͢Δ
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-FOTͷͨΊͷίʔυੜ
@optics
data class Profile(val name: String, val statusMessage: StatusMessage) {
companion object
}
/ /
Generated code
val Profile.Companion.name: Lens get() = Lens(
get = { profile: Profile
->
profile.name },
set = { profile: Profile, value: String
->
profile.copy(name = value) }
)
val Profile.Companion.statusMessage: Lens get() = Lens(
get = { profile: Profile
->
profile.statusMessage },
set = { profile: Profile, value: StatusMessage
-
>
profile.copy(statusMessage = value) }
)
wDPNQBOJPOPCKFDUͷ֦ுϓϩύςΟܦ༝Ͱɺੜ͞Εͨ
-FOT͕ར༻Մೳ
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-FOTͷͨΊͷίʔυੜ
val composedLens: Lens = User.profile.statusMessage
//
Generated code
val Lens.statusMessage: Lens inline get() =
this + Profile.statusMessage
val User.Companion.profile: Lens inline get() = Lens(
get = { user: User
->
user.profile },
set = { user: User, value: Profile
->
user.copy(profile = value) }
)
val Profile.Companion.statusMessage: Lens inline get() = Lens(
get = { profile: Profile
->
profile.statusMessage },
set = { profile: Profile, value: StatusMessage
-
>
profile.copy(statusMessage = value) }
)
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-FOTͷͨΊͷϢʔςΟϦςΟؔ
val modifiedUser1 = User.profile.name.modify(user) { it.uppercase() }
val modifiedUser2 = User.profile.statusMessage.text
.modify(modifiedUser1) { it.uppercase() }
val result = User.profile.statusMessage.updatedTime
.modify(modifiedUser2) { System.currentTimeMillis() }
wෳͷϓϩύςΟͷҰׅมߋۤख
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-FOTͷͨΊͷϢʔςΟϦςΟؔ
val result = user.copy {
User.profile.name transform { it.uppercase() }
inside(User.profile.statusMessage) {
StatusMessage.text transform { it.uppercase() }
StatusMessage.updatedTime set System.currentTimeMillis()
}
}
wDPQZ
Ͱ-FOTΛΑΓศརʹ͑Δ
wJOTJEF
ಛఆͷϑΥʔΧεͷγϣʔτΧοτ
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-FOTͷͨΊͷϢʔςΟϦςΟؔ
val modifiedUser1 = User.profile.name.modify(user) { it.uppercase() }
val modifiedUser2 = User.profile.statusMessage.text
.modify(modifiedUser1) { it.uppercase() }
val result = User.profile.statusMessage.updatedTime
.modify(modifiedUser2) { System.currentTimeMillis() }
val result = user.copy {
User.profile.name transform { it.uppercase() }
inside(User.profile.statusMessage) {
StatusMessage.text transform { it.uppercase() }
StatusMessage.updatedTime set System.currentTimeMillis()
}
}
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ଞϥΠϒϥϦͱͷ࿈ܞ
val messageState = remember { mutableStateOf(message) }
val messageStateFlow = MutableStateFlow(message)
messageState.updateCopy {
StatusMessage.text transform { it.uppercase() }
}
messageStateFlow.updateCopy {
StatusMessage.text set "newText"
}
wDPQZ
.VUBCMF4UBUF.VTUBCMF4UBUF'MPXͰར༻Մೳ
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ଞϥΠϒϥϦͱͷ࿈ܞ
val messageState = remember { mutableStateOf(message) }
val messageStateFlow = MutableStateFlow(message)
val messageSharedFlow = MutableSharedFlow()
val textState: State = messageState.optic(StatusMessage.text)
val textStateFlow: StateFlow =
messageStateFlow.optic(StatusMessage.text)
val textSharedFlow: SharedFlow =
messageSharedFlow.optic(StatusMessage.text)
wPQUJD
-FOTΛͬͯ৽͍͠4UBUF'MPXΛੜ
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-FOTͷݶք
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-FOTͷݶք
data class User(
val id: Int,
val profile: Profile,
val friends: Map
)
fun getUserFriendProfile(user: User, friendUserId: Int): Profile? =
User.friends.
???
.get(user)
w-FOTEBUBDMBTTΛѻ͏ۜͷؙͰͳ͍
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-FOTͷݶք
data class User(val id: Int, val profile: Profile)
sealed class Profile {
abstract val name: String
abstract val statusMessage: StatusMessage
data class BasicProfile(
override val name: String,
override val statusMessage: StatusMessage) : Profile()
data class PremiumProfile(
override val name: String,
override val statusMessage: StatusMessage,
val nameDecorationMetadata: String) : Profile()
}
fun maybeSetNameDecorationMetadata(user: User, newMetadata: String): User =
User.profile.
???
.set(user, newMetadata)
w-FOTEBUBDMBTTΛѻ͏ۜͷؙͰͳ͍
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0QUJDT
w"SSPXLUͷ0QUJDTҎԼͷͭͰߏ͞Ε͍ͯΔ
w 5SBWFSTBM
w 0QUJPOBM
w -FOT
w 1SJTN
w *TP
wԼʹߦ͘΄Ͳೳྗ͕૿͑Δ͕
ద༻Մೳൣғڱ·Δ
IUUQTBSSPXLUJPMFBSOJNNVUBCMFEBUBJOUSPNBOZPQUJDTUPSVMFUIFNBMM
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5SBWFSTBM
interface Traversal {
fun modify(source: S, map: (focus: A)
->
A): S
}
w-JTUͳͲɺෳݸͷͷߋ৽͕Ͱ͖Δ
wLPUMJODPMMFDUJPOTNBQΛҰൠԽͨ͠ɺNPEJGZ
͕ར༻Մೳ
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5SBWFSTBM
data class UserGroup(val name: String, val users: List)
data class Profile(val name: String, val statusMessage: StatusMessage)
data class StatusMessage(val text: String, val updatedTime: Long)
fun updateAllUpdatedTime(group: UserGroup): UserGroup =
UserGroup.users.modify(group) { user
-
>
user.map {
User.profile.statusMessage.updatedTime.set(it, System.currentTimeMillis())
}
}
fun updateAllUpdatedTimeWithTraversal(group: UserGroup): UserGroup =
UserGroup.users.every.profile.statusMessage.updatedTime
.set(group, System.currentTimeMillis())
wNBQ
Λ5SBWFSTBMͰஔ͖͑Δ
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0QUJPOBM
interface Optional : Traversal {
override fun modify(source: S, map: (focus: A)
->
A): S
fun getOrNull(source: S): A?
}
w-JTU.BQͳͲͷίϨΫγϣϯ͔ΒҰͭͷΛऔΓग़ͤΔ
wHFU0S/VMM
Ͱࣦഊ͢ΔՄೳੑͷ͋ΔॲཧΛදݱՄೳ
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0QUJPOBM
data class User(
val id: Int,
val profile: Profile,
val friends: Map
)
fun getUserFriendProfile(user: User, friendUserId: Int): Profile? {
val friendOptional: Optional = User.friends.index(friendUserId)
return friendOptional.profile.getOrNull(user)
}
w.BQ ,
7 Λ0QUJPOBMͰѻ͏
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1SJTN
interface Prism : Optional {
override fun modify(source: S, map: (focus: A)
->
A): S
override fun getOrNull(source: S): A?
fun reverseGet(focus: A): S
}
wTFBMFEDMBTTͷΫϥε֊ͷදݱʹΘΕΔ
wSFWFSTF(FU
ͰϑΥʔΧε͔Βιʔε͕ߏஙՄೳ
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1SJTN
sealed class Profile {
data class BasicProfile() : Profile()
data class PremiumProfile() : Profile()
}
val basicProfilePrism: Prism =
Profile.basicProfile
val premiumProfilePrism: Prism =
Profile.premiumProfile
wαϒΫϥεͷΫϥε໊ͷ1SJTN͕ੜ͞ΕΔ
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1SJTN
data class User(val id: Int, val profile: Profile)
sealed class Profile {
abstract val name: String
abstract val statusMessage: StatusMessage
data class BasicProfile(
override val name: String,
override val statusMessage: StatusMessage) : Profile()
data class PremiumProfile(
override val name: String,
override val statusMessage: StatusMessage,
val nameDecorationMetadata: String) : Profile()
}
fun maybeSetNameDecorationMetadata(user: User, newMetadata: String): User =
User.profile.premiumProfile.nameDecorationMetadata.set(user, newMetadata)
wTFBMFEDMBTTΛ1SJTNͰѻ͏
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-FOT
interface Lens : Optional {
override fun modify(source: S, map: (focus: A)
->
A): S
fun get(source: S): A
}
w(FUUFSͱ4FUUFS͕ར༻Ͱ͖Δ
wHFU
ͰϑΥʔΧεΛ࣮֬ʹऔಘՄೳ
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*TP
interface Iso : Prism, Lens {
override fun modify(source: S, map: (focus: A)
->
A): S
override fun reverseGet(focus: A): S
override fun get(source: S): A
}
wͭͷܕͷؒͰɺใͷଛࣦແ͠ͷ૬ޓม͕Մೳ
w-FOTͱ1SJTNͷ྆ํͷೳྗΛ࣋ͭ
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*TP
data class StatusMessage(val text: String, val updatedTime: Long)
val statusMessageToPairIso: Iso>
= Iso(
get = { it.text to it.updatedTime },
reverseGet = { StatusMessage(it.first, it.second) }
)
@JvmInline
value class UserId(val id: Int)
fun UserId.getValue(): Int = UserId.id.get(this)
fun Int.toUserId(): UserId = UserId.id.reverseGet(this)
w*TPʹΑΔܕม
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0QUJDT·ͱΊ
0QUJDTaؔ NPEJGZ
HFU0S/VMM
SFWFSTF(FU
HFU
5SBWFSTBM ̋ ✕ ✕ ✕
0QUJPOBM ̋ ̋ ✕ ✕
1SJTN ̋ ̋ ̋ ✕
-FOT ̋ ̋ ✕ ̋
*TP ̋ ̋ ̋ ̋
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0QUJDT·ͱΊ
w5SBWFSTBMෳݸͷશͯͷߋ৽
w0QUJPOBMίϨΫγϣϯͷҰ෦ͷऔಘ
w1SJTNTFBMFEDMBTTͷΫϥε֊ͷදݱ
w-FOT(FUUFS 4FUUFS
w*TPͭͷܕؒͷ૬ޓม
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·ͱΊ
w-FOTΛͬͯEBUBDMBTTͷૢ࡞Λ؆୯ʹهड़Մೳ
w-FOT(FUUFSͱ4FUUFSͷɻࣗ࡞ͯ͠ΈΛཧղ
w"SSPXLUͷίʔυੜͰɺ-FOTΛຖճఆٛͤͣʹར༻Մೳ
wίϨΫγϣϯɺTFBMFEDMBTTɺWBMVFDMBTTͷૢ࡞ʹ0QUJDT
Λར༻͢Δ