Quoting Richard O'Keefe <o...@cs.otago.ac.nz>:
On 3/10/2011, at 7:15 AM, Du Xi wrote:
I guess this is what I want, thank you all. Although I still wonder
why something so simple in C++ is actually more verbose and
requires less known features in Haskell...What was the design
intent to disallow simple overloading?
It's not "SIMPLE overloading" you are asking for,
but "AD HOC overloading", which may look simple, but really isn't.
Taking your C++ f() example, in what sense are the two functions
_the same function_?
I understand that functions with the same name but different type
signatures are not the same function, but are a family of
functions,probably representing the same concept.
Also
identityInHaskell::a->a
identityInHaskell x = x
--I don't know if this is implemented as runtime polymorphism or
compile-time polymorphism,
--but it is possible to implement this as compile-time polymorphism.
and
template< typename T > T IdentityInCPP( T x ){ return x; }
are families of different functions.
I think the problem I have encountered can be broken down to 2 problems:
1. Haskell doesn't have a way to represent mapping from one type to
another (consider metafunctions in C++), which is addressed by
TypeFamilies.
2. Haskell disallows ad-hoc overloading. But I think implementing
ad-hoc overloading itself should be no more complex than implementing
type classes, perhaps it would tear a hole somewhere else?
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