Definition/Documentation of "|" in mini notation

Hi. In some performance I've seen "[a|b|c]" apparently for making a (pseudo) random choice. It's currently not in .

I see the implementation ( but it's hard to deduce the intention, in particular, the interaction with other features of the notation, as in

*** Exception: Syntax error in sequence:
unexpected ","

I am not seeing any test cases (I looked in ParseTest.hs). If you could post some (here), I can collect them into a PR for the repo.

It is a semantical function? The implementation
( is calling toPat on the children of TPat_CycleChoose.

But it's more, since it also diversifies the randomness (by fudging the timing).