Nested match patterns

[fvogels]

While in the progress of developing a new translation target, I need to deal with nested patterns, such as

match pair {
  (Foo, Foo) => A,
  (Foo, Bar) => B,
  (Bar, Foo) => C,
  (Bar, Bar) => D
}

which, due to restrictions imposed by the target language, I need to restructure as follows:

match fst(pair) {
  Foo => match snd(pair) {
    Foo => A,
    Bar => B
  },
  Bar => match snd(pair) {
    Foo => C,
    Bar => D
  }
}

I wondered if this logic was already implemented somewhere. I did check the available rewrites, but as far as I can tell, none of them performs this specific transformation. I also experimented with the OCaml and C backends, but based on their output it doesn't look like they require this transformation.