Add inlining to Polysemy.Writer

[KingoftheHomeless]

I forgot to add those wacky INLINE pragmas...

[isovector]

I wonder if we could convince Loopbreaker to insert these automatically. @TheMatten any ideas?

[TheMatten]

You mean something like INLINE to all functions that manipulate Sem type, or all functions in module?

[isovector]

Just things that are wrappers around send.

[isovector]

I think it's a good idea to manually mark your interpreters as INLINE, but the actions should technically be INLINEABLE CONLIKE, which is more of a mouthful than I want to ask from users. The TH correctly generates the right stuff.

[TheMatten]

Generally (and this should be compatible with reimplementation in the future), I would like to have {-# ANN foo Loopbreaker #-}, that would just "do it's magic" and add required annotations and stuff.