In my (admittedly newbie) experience, it's particularly useful when application ...

Xophmeister on July 18, 2022 | parent | context | favorite | on: Concatenation is composition

In my (admittedly newbie) experience, it's particularly useful when application of your function is going to be in a context where η-reduction is natural. For example, your fmap is going to look cleaner without a wrapping lambda inside it.