[Haskell-cafe] What is an "expected type" ...

Dan Piponi dpiponi at gmail.com
Sun Jun 28 14:56:09 EDT 2009


I really dislike this error message, and I think the terms are
ambiguous. I think the words 'expected' and 'inferred' apply equally
well to the term, and the context in which it has been found. Both of
the incompatible types were 'inferred', and 'unexpected' is a property
of the combination, not a property of one or the other.
--
Dan

On Sun, Jun 28, 2009 at 8:24 AM, Martijn van
Steenbergen<martijn at van.steenbergen.nl> wrote:
> Hi Michael,
>
> michael rice wrote:
>>
>> as opposed to an "inferred type"?
>
> Can you deduce from the following example?
>
>> Prelude> let foo = () :: Int
>> <interactive>:1:10:
>>    Couldn't match expected type `Int' against inferred type `()'
>>    In the expression: () :: Int
>>    In the definition of `foo': foo = () :: Int
>>
>
> Hope this helps!
>
> Martijn.
>
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