don't make frame_fractional an instance
Instead, just add a concrete instance for ↦. This prevents TC search from trying AsFractional framing everywhere.
Let us see how much performance removing that instance brings, and how much convenience it costs. On Iris itself, this speeds up heap_lang.lib by 0.8%. iris/examples results can be found here.
Fixes #351 (closed)
Edited by Ralf Jung