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Raúl Raja Martínez raulraja

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raulraja / st.kt
Created November 14, 2020 19:26
Marco's question in slack
package arrow.prelude.test
import arrow.continuations.generic.DelimContScope
import arrow.continuations.generic.DelimitedScope
abstract class ST<S, A> @PublishedApi internal constructor() {
companion object {
operator fun <S, A> invoke(a: () -> A): ST<S, A> {
val memo by lazy(a)
return object : ST<S, A>() {
@raulraja
raulraja / IO.kt
Created April 17, 2020 20:06
Kinds without uncheched casts
/** Bifunctor IO */
class IO<out E, out A> :
`*`<IO<*, *>>,
`*-*`<IO<*, *>, A>,
`*-*-*`<IO<*, *>, E, A> {
fun <B> fmap(f: (A) -> B): IO<Nothing, B> = TODO()
fun <B> flatMap(f: (A) -> `*-*`<IO<*, *>, B>): IO<Nothing, B> = TODO()
fun <C, D> bimap(fl: (E) -> C, fr: (A) -> D): IO<C, D> = TODO()
companion object {
@raulraja
raulraja / AutoCancellation.kt
Last active March 8, 2020 12:15
Arrow Fx. Auto cancels without leaving to user discipline to check for `isAlive`. Examples by @nomisRev
import arrow.fx.*
import arrow.fx.extensions.*
import arrow.fx.typeclasses.*
import arrow.fx.extensions.io.bracket.guaranteeCase
fun <A> IOOf<A>.onCancel(token: IOOf<Unit>): IO<A> =
guaranteeCase { case ->
when (case) {
ExitCase.Canceled -> token
else -> IO.unit
@raulraja
raulraja / rules.kt
Created March 5, 2020 17:51
Validation rules abstracting strategies with operations as extension functions
package arrow.rules.test
import arrow.Kind
import arrow.core.Either
import arrow.core.EitherPartialOf
import arrow.core.Nel
import arrow.core.NonEmptyList
import arrow.core.Validated
import arrow.core.ValidatedPartialOf
import arrow.core.extensions.either.applicativeError.applicativeError
@raulraja
raulraja / TwitterHandle.kt
Created February 20, 2020 12:16
Type Refinements with Type Proofs in Kotlin
/* Coming up ~ April 2020 */
package test
import arrow.*
inline class TwitterHandle(val handle: String) {
companion object : Refined<String> {
override val validate: String.() -> Map<String, Boolean> = {
mapOf(
"Should start with '@'" to startsWith("@"),
@raulraja
raulraja / prelude.kt
Created January 7, 2020 23:16
Daydreaming proofs as contracts
package arrow.meta.ide.plugins.proofs.contracts
import kotlin.contracts.Effect
import kotlin.contracts.ExperimentalContracts
interface TypeLevelEffect : Effect
interface Declaration : Effect
fun declaration(): Declaration = TODO()
@raulraja
raulraja / toStringReplacement.meta.kt
Created November 5, 2019 12:48
[toString] replacement, originally discussed in https://kotlinlang.slack.com/archives/C7L3JB43G/p1572884683059400
package arrow.meta.plugins.helloWorld
import arrow.meta.Meta
import arrow.meta.Plugin
import arrow.meta.invoke
import arrow.meta.phases.analysis.ElementScope
import arrow.meta.quotes.ClassScope
import arrow.meta.quotes.Scope
import arrow.meta.quotes.Transform
import arrow.meta.quotes.classOrObject
@raulraja
raulraja / DefaultDicitionary.kt
Last active June 26, 2019 23:10
DefaultDictionary
package dictionary
/**
* A default dictionary is a map that provides a default concrete Monoid empty value for [B]
* Inspired by some of the examples of https://kotlinexpertise.com/default-map-in-kotlin/
* https://twitter.com/raulraja/status/1141697899383992325
*/
data class DefaultDictionary<A, B>(val empty: B, val underlying: Map<A, B> = emptyMap()) : Map<A, B> by underlying {
/**
@raulraja
raulraja / di.kt
Last active October 30, 2021 16:30
Simple Kotlin DI
package com.fortyseven.fptraining
import arrow.core.Either
import arrow.core.right
import arrow.effects.IO
import arrow.effects.extensions.io.fx.fx
data class Account(val balance: Int)
data class AccountEntity(val balance: Int)
@raulraja
raulraja / Capabilities.kt
Last active February 26, 2019 15:44
Kotlin transformers encoding for `Death of Final Tagless` by John De Goes.
package arrow.effects.zio.example
/** Capabilities aggregation ala Kotlin **/
class Capabilities(
console: Console,
random: Random
) : Console by console, Random by random