modify

common open fun <A> TVar<A>.modify(f: (A) -> A)

Modify 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.modify { it * 2 }
  }
  //sampleEnd
  println(result)
}

modify(f) = write(f(read()))

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