is ```private fun <E, T> Raise<E>.contramap(f: (T) -> E): Raise<T> = object : Raise<T> { override ...

# arrow

[phldavies]

is

private fun <E, T> Raise<E>.contramap(f: (T) -> E): Raise<T> = object : Raise<T> {
  override fun raise(e: T) = raise(f(e))
}

sane, assuming the mapped raise doesn't escape the bounds of the original raise?

[Youssef Shoaib [MOD]]

It's sane yes, but withError is preferred, mostly because it can do it inline

[phldavies]

I'm storing a reference to the contramapped raise in a class (that lives entirely within the scope), otherwise I'd have used withError 🙂

[Youssef Shoaib [MOD]]

Yeah that's fine then! We've had Raise implementations that basically did that (e.g. IorRaise), but I was keen to move away from that to prepare for context parameters (so that recover would work naturally and replace the Raise), however as an implementation it's absolutely fine

[phldavies]

ended up just holding the anonymous Raise in a field in the scoped-raise type: https://github.com/arrow-kt/arrow/pull/3581/files#diff-a4074810ec25a2fa4d260ce79bf35b76759b9d55c4c7cf437e729766b31f8914R17-R19