mustSatisfyAnyOf fails the expected logic

[blamario]

Summary

The function is admittedly completely undocumented, but from its type signature

mustSatisfyAnyOf :: forall i o. [TxConstraints i o] -> TxConstraints i o

and the name, I would expect that it's meant to be equivalent to any, meaning if any of the items in the argument list is satisfied, the result will be satisfied as well. In a bit of pseudo-notation,

satisfied (mustSatisfyAnyOf xs) == any satisfied xs

As a reminder, the TxConstraints type is basically a conjunction of a list of TxConstraint, so it acts as an all; its mempty implementation is an empty list and is always trivially satisfied. So we can expand this to

satisfied (mustSatisfyAnyOf xs) == any satisfied xs == any (all satisfied) xs

That's not what happens. The actual function implementation is

mustSatisfyAnyOf = singleton . MustSatisfyAnyOf . concatMap txConstraints

The first thing the function does is to take a list of the conjunction lists flatten the list of [[TxConstraint]], so we end up with

satisfied (mustSatisfyAnyOf xs) == any (any satisfied) xs

Steps to reproduce

mustSatisfyAnyOf [mempty]

always fails.

Expected behavior

mustSatisfyAnyOf [mempty]

should be equal to mempty, i.e. it should be trivial to satisfy.

System info (please complete the following information):

• OS: Ubuntu
• Version 21.10
• 58c093a