Re: OT: Language War (Re: "C" Manual)

[David Teague <dbt@tinuviel.cs.wcu.edu>]

William, Richard, and all:

Stroustrup has said that if you find you have to cast, (much) your
design is flawed.

--David Teague



On Tue, 1 Jan 2002, William T Wilson wrote:

> On Tue, 1 Jan 2002, Richard Cobbe wrote:
> 
> > > | Casting you can't really get away from nor do you really need to.  In fact
> > > | the more strongly typed the language is, the more casting you have to do.
> > > 
> > > This statement is incorrect.
> > 
> > Agreed.
> 
> I suppose I will agree as well, I was not meaning to include dynamically
> typed languages in the original statement, I just didn't say that :}
> Really it was not a very good statement to make, although in the original
> context it wasn't so bad :}
> 
> > However, I think that the flexibility of a type system is more
> > important than its `strength' for removing the need for casts.
> 
> I will go along with that as well.  In ML for instance (and other
> languages as well) there is parametric polymorphism which give you a lot
> of the flexibility of dynamic typing while still retaining much of the
> error checking of static typing.  This is different from the
> "polymorphism" found in C++ in which you can have virtual functions (which
> still require the programmer to provide all the different implementations)
> and inheritance (which only permits polymorphism within a very limited set
> of types).  Although I do not know Haskell my understanding is that this
> is how it works as well.
> 
> For instance you could have:
> fun times x y = x * y;
> 
> You could then apply this function to either reals, ints, or one of each
> and then it would return the appropriate type.  The compiler will trace
> the execution through the function, deducing which are legal types from
> the operators and functions used within the function.  In this way you do
> not need to write a separate function for each combination of types your
> functions might want to operate on, even though ML is a statically typed
> language.
> 
> But because the checking is all done at compile-time you do not have much
> risk of runtime errors due to type problems.
> 
> 
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> 

--David
David Teague, dbt@cs.wcu.edu
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