Omit the conditional for case expressions with a single alternative.
Omit the conditional for case expressions with a single alternative.

Whenever the user writes a non-exhaustive case expression, GHC inserts the
appropriate pattern error default clause; in fact, Core doesn't even allow
non-exhaustive case expressions, which means that any case expression with
a single alternative must be purely to evaluate and/or pick apart thunks, so
we can just skip the conditional entirely and stick to the bindings.

beni55/haste-compiler,joelburget/haste-compiler,joelburget/haste-compiler,joelburget/haste-compiler,nyson/haste-compiler,santolucito/haste-compiler,joelburget/haste-compiler,crodjer/haste-compiler,kranich/haste-compiler,jtojnar/haste-compiler,akru/haste-compiler,santolucito/haste-compiler,nyson/haste-compiler,jtojnar/haste-compiler,crodjer/haste-compiler,crodjer/haste-compiler,akru/haste-compiler,kranich/haste-compiler,akru/haste-compiler,beni55/haste-compiler,szatkus/haste-compiler,jtojnar/haste-compiler,kranich/haste-compiler,crodjer/haste-compiler,szatkus/haste-compiler,akru/haste-compiler,kranich/haste-compiler,beni55/haste-compiler,szatkus/haste-compiler,santolucito/haste-compiler,beni55/haste-compiler,szatkus/haste-compiler,jtojnar/haste-compiler,nyson/haste-compiler,nyson/haste-compiler,akru/haste-compiler,santolucito/haste-compiler,crodjer/haste-compiler