Proposal: don't print constraints in parens

Currently we print constraints in parentheses:

  • No instance for (Num Bool) arising from the literal ‘1’
  • Could not deduce (C a x)

I propose to use quotes instead:

  • No instance for ‘Num Bool’ arising from the literal ‘1’
  • Could not deduce ‘C a x’

Reasoning: This is more uniform - constraints are types, and types are printed without parentheses. Error messages usually use quotes to separate text from code.

Counterargument: some people write constraints in parentheses and that makes it easier to copy-paste.