set

open fun <A> TVar<A>.set(a: A)

Set the value of a TVar.

import arrow.fx.stm.TVar
import arrow.fx.stm.atomically

suspend fun main() {
  //sampleStart
  val tvar = TVar.new(10)
  val result = atomically {
    tvar.set(20)
  }
  //sampleEnd
  println(result)
}

Similarly to value this comes with a few guarantees:

For multiple writes to the same TVar in a transaction only the last will actually be performed
When committing the value inside the TVar, at the time of calling set, has to be the same as the current value otherwise the transaction will retry

open operator fun <A> TArray<A>.set(i: Int, a: A)

Set a variable in the TArray.

import arrow.fx.stm.TArray
import arrow.fx.stm.atomically

suspend fun main() {
  //sampleStart
  val tarr = TArray.new(size = 10, 2)
  val result = atomically {
    tarr[5] = 3

    tarr[5]
  }
  //sampleEnd
  println("Result $result")
}

Throws if i is out of bounds.

This function never retries.

open operator fun <K, V> TMap<K, V>.set(k: K, v: V)

Alias for STM.insert

import arrow.fx.stm.TMap
import arrow.fx.stm.atomically

suspend fun main() {
  //sampleStart
  val tmap = TMap.new<Int, String>()
  atomically {
    tmap[1] = "Hello"
  }
  //sampleEnd
}