[Ur] Signature Help

Adam Chlipala adamc at impredicative.com
Mon May 9 17:36:03 EDT 2011


Marc Weber wrote:
> Very often you can get close by aksing the compiler to give hints. Eg by
>
>
> let
>
>    f :: string ->  int = fun x ->  x * x
>
> in f 20
>
> you see that string doesn't match the integer/float operation.
> So the compiler will tell about a missmatch talking about what it
> expects.
>    

Given David's problem, it should be even simpler to include a signature 
entry for the function in the .urs file, giving it type [int].  The 
compiler will surely complain about that and give the proper type.

BTW, readers should keep in mind that Marc's example above isn't using 
valid Ur/Web syntax. ;)

David, if you are having trouble writing your function in the first 
place, not just determining its type, feel free to ask again with more 
problem detail.



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