[Haskell-cafe] ????Pattern match(es) are overlapped???

Arjan van IJzendoorn afie at cs.uu.nl
Mon Mar 22 11:29:31 EST 2004


>    newtype Method = Method String
>    getMethod = Method "GET"
>    putMethod = Method "PUT"
>
>    [...]
>
>    doMeth getMethod = ...
>    doMeth putMethod = ...

For Haskell the last two lines look both like pattern-matching on a variable
which always matches. You might as well have written:

doMeth x = ...
doMeth y = ...

There is no macro facility in Haskell so you cannot give patterns a name
like you do in line 2 and 3.
You will have to write:

doMeth (Method "GET") = ...
doMeth (Method "PUT") = ...

Good luck, Arjan



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