Enables currying for function/lambda/constructor
@Curry
fun testHotness(person: String, chili: String) {}
val chilis = listOf("Cayenne","Habanero", "Carolina Reaper")
// normally
chilis.map{chili -> testHotness("Peter", chili)}
// with currying, you can preload the function
val testerPeter = testHotness("Peter")
chilis.map(testerPeter)apply plugin: 'kotlin-kapt'
repositories {
maven { url 'https://jitpack.io' }
}
dependencies {
kapt 'in.abaddon.tartarus:unholy-curry:0.0.4'
compileOnly 'in.abaddon.tartarus:unholy-curry:0.0.4'
}- annotate function/lambda/constructor with
@Curry - import subpackage
curry - have fun ;)
package com.example.foo
import com.example.foo.curry.*
class Spice
@Curry constructor(val name: String, val color: Int, hotness: Int) {
@Curry
val enhance = {factor: Double, quantity: Int, degree: Int -> ... }
@Curry
fun mitigate(drink: String, quantity: Int, degree: Int): Int { ... }
}
object MainObj {
fun doSomething() {
val s1 = Spice("GhostPepper",0xF00,1000000)
s1.enhance(2.5, 50, 90)
s1.mitigate("Milk",100,90)
// with currying
val s2 = createSpice("GhostPepper")(0xF00)(1000000)
s2.enhance(2.5)(50)(90)
s2.mitigate("Milk")(100)(90)
}
}Recap:
- Method signature consists of method name and ordered parameter list
- Only types are significant for the parameter list and the name of parameter is ignored
- The return type is not included
It could happen that generated curried function clashes with the existing method signature. In such a case, you can simply override the name.
class Pan {
fun cook(ingredients: String) { ... }
// Requires custom name because the curried function will clash with method signature above.
@Curry(name = cookSmoothly)
fun cook(ingredients: String, heat: Int, duration: Double){ ... }
}
pan.cook("chicken", 90, 5.0)
pan.cookSmoothly("chicken")(90)(5.0)We'd like to preload the function cook and apply it to the list of meats. Unfortunately the parameter meat: String, which is needed for the map function, is at the beginning. We can rearrange the order of the parameters for curried function by passing a list of indexes of parameters in the desired order.
class Pan {
@Curry(order = intArrayOf(1,2,0)) // (heat, duration, meat)
fun cook(meat: String, heat: Int, duration: Double){ ... }
}
val cookWellDone = pan.cook(/*heat*/ 95)(/*duration*/ 10.0)
listOf("Chicken","Beef","Pork").map(cookWellDone)
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