Right. Now that you posted this I vaguely remember having seen the concat method somewhere before.
But since there is an open issue about providing the means to customize the filenames of generated resources, let me tell you that on Windows 10 I have already hit the filename character limit more than once, due to the way that Hugo generates the resources names.
Shorter filenames by default, for Hugo’s generated resources, would be preferable.
Why not use a shorter hash function like SHA-1 to generate them?
P.S. Also I am re-opening the topic for a limited amount of time in case others want to share their way of customizing the filenames.