[Haskell-beginners] A very counterintuitive behaviour of Haskell

[jean verdier]

You have defined 2 functions that are called f and only the last
definition is used (f x = "no").
The definition you want should be written
let f 7 = "ok"; f x = "no"
so the function is defined once.
The problem comes from using the interpreter and not from haskell.


On Thu, 2011-01-27 at 15:55 +0100, Renzo Orsini 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?
> 
> Thank you very much.
> 
> Renzo
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://www.haskell.org/mailman/listinfo/beginners