Claus Reinke wrote:
Still, I would really like a "just the facts, please" mode for GHC, with
less text and more type signatures (especially for the contexts of type
mismatches). Error messages simply not including the
information I need has become my main issue with GHC messages,
and seems to be a common thread over many tickets and threads
apparently discussing phrasing (eg, expected/inferred: who expects
and why, and what is the inference based on?).
FWIW, the suggestion I floated has less text than the current message
while preserving all the type and expression information ;)
(Though it doesn't necessarily generalize to cover similar messages like:
Prelude> :t (\x -> x) :: a -> b
<interactive>:1:7:
Couldn't match expected type `b' against inferred type `a'
`b' is a rigid type variable bound by
the polymorphic type `forall a b. a -> b' at <interactive>:1:0
`a' is a rigid type variable bound by
the polymorphic type `forall a b. a -> b' at <interactive>:1:0
In the expression: x
)
Just, please, keep in mind that there is no one-size-fits-all:
improving a message for one group of users might well make
it less useful for another group.
+1.
There're worlds of difference between the kinds of error messages
suitable for beginners, vs "regular users", vs type-level programmers.
Also, while a user may have some given level of understanding, the level
of messaging they'll want can vary a lot depending on the task a hand.
--
Live well,
~wren
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