[Haskell-beginners] A very counterintuitive behaviour of Haskell

[Magnus Therning]

On Thu, Jan 27, 2011 at 14:55, Renzo Orsini <renzo.orsini at gmail.com> wrote:
> In studying Haskell, I produced the following output from GHC:
>
> xxx-3:~ xxx$ GHCi
> GHCi, version 6.12.3: http://www.haskell.org/ghc/  :? for help
> Loading package ghc-prim ... linking ... done.
> Loading package integer-gmp ... linking ... done.
> Loading package base ... linking ... done.
> Loading package ffi-1.0 ... linking ... done.
> Prelude> let f 7 = "ok"
> Prelude> let f x = "no"
> Prelude> f 3
> "no"
> Prelude> f 7
> "no"
>
> I suppose it is correct. However, for someone who is interested in the language, it seems very counterintuitive... Somebody would be so kind to explain to a neophyte this "feature" of the language?

I suppose it comes down to pattern matching being on form, not on value.

/M

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Magnus Therning                      OpenPGP: 0xAB4DFBA4
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