The signature didn't change, but the parameter names. Sorry this was indeed breaking in the

alpha

, we had some inconsistencies in the parameter names and we aligned them. So if you're using named parameters for the lambdas you need to update accordingly.

fun Raise<String>.failure(): Int = raise("failure")

recover(
  block = { failure() },
  recover = { -1 }
) shouldBe -1

Here is the PR showing the alignment in the API and type argument names. https://github.com/arrow-kt/arrow/pull/2987 We followed naming from Kotlin Std which uses

block

for such lambda parameters.