rails/rails — comment on commit 60dad828aefa41703c0eee3863a7141c56caa7da
File: activemodel/lib/active_model/validations/length.rb line 32
By Nielsomat:

@exviva the use case for which I implemented this was a 3rd party library (devise) that allows the configuration of a length range but not min or max individually, let alone only one of the two.

IMO this is perfectly legit and I actually find X..Float::INFINITY more readable than only supplying a minimum and no maximum. It conveys intention more clearly.