I guess this is late fallout from my long ago refactor that changed the
argument order for the patch sequencing operators. This isn't covered by
unit tests since they only use FLs. And the type checker cannot flag this
error because apply is monadic and Trees aren't tagged with witnesses.
1 patch for repository /home/ben/src/darcs/sent:
patch 8c3031c28048eb2d14af5eb26ad96cb57d33d69c
Author: Ben Franksen <ben.franksen@online.de>
Date: Wed Mar 6 11:40:28 CET 2019
* fix a (serious!) bug in instance Apply (RL p)
I tried changing this code to an error, and the entire shell test
suite passes too. So I guess we dodged the bullet because it's
never actually used anywhere.