I feel so unbelievably ignorant now. I thought with all the IORefs in the type
checking process that zonking did this in these refs. Somehow I started
thinking that some of these remained in SDocs, not thinking showSDoc is pure
and results in a String, which holds no IORefs.
Does this mean
Haskell is a *functional* language. Consider
say $ pre-zonk: ++ pp all_expr_ty
zonkTcType all_expr_ty
say $ post-zonk: ++ pp all_expr_ty
pp is a pure function; it is given the same input both times, so of course it
produces the same output.
If you collect the result of
