Static typing

[Dirk Thierbach]

Pascal Costanza <costanza at web.de> wrote:
> Dirk Thierbach wrote:
>> You cannot take an arbitrary language and attach a good static type
>> system to it. Type inference will be much to difficult, for example.
>> There's a fine balance between language design and a good type system
>> that works well with it.

> Right. As I said before, you need to reduce the expressive power of the 
> language.

Maybe that's where the problem is. One doesn't need to reduce the
"expressive power". I don't know your particular application, but what
you seem to need is the ability to dynamically change the program
execution. There's more than one way to do that. And MOPs (like
macros) are a powerful tool and sometimes quite handy, but it's also
easy to shoot yourself severly into your own foot with MOPs if you're
not careful, and often there are better solutions than using MOPs (for
example, apropriate flexible datatypes).

I may be wrong, but I somehow have the impression that it is difficult
to see other ways to solve a problem if you haven't done it in that
way at least once. So you see that with different tools, you cannot do
it in exactly the same way as with the old tools, and immediately you
start complaining that the new tools have "less expressive power",
just because you don't see that you have to use them in a different
way.  The "I can do lot of things with macros in Lisp that are
impossible to do in other languages" claim seems to have a similar
background.

I could complain that Lisp or Smalltalk have "less expressive power"
because I cannot declare algebraic datatypes properly, I don't have
pattern matching to use them efficiently, and there is no automatic
test generation (i.e., type checking) for my datatypes. But there
are ways to work around this, so when programming in Lisp or Smalltalk,
I do it in the natural way that is appropriate for these languages,
instead of wasting my time with silly complaints. 

The only way out is IMHO to learn as many languages as possible, and
to learn as many alternative styles of solving problems as possible.
Then pick the one that is apropriate, and don't say "this way has
most expressive power, all others have less". In general, this will
be just wrong.

- Dirk