soft typing for prolog 
Author Message
 soft typing for prolog

I'm interested in soft typing systems and would like to know if
anybody knows of such systems developed for prolog, either on a
theoretical level or implemented.


Sat, 22 May 2004 18:13:57 GMT  
 soft typing for prolog
Whats a "soft typing system" ?

Martin Sondergaard,

Mon, 24 May 2004 04:43:29 GMT  
 soft typing for prolog


> Whats a "soft typing system" ?

A soft typing system is a sort of combination of a static and a
dynamic type system. In static type systems the type check is done at
compile time while in
the case of dynamic type systems the type check is postponed until
runtime. The former approach has the advantage that the compiled
program does not have to do the type check while the program is
running. On the other hand, there are some programs that are
well-typed, but will be rejected by the type checker because proving a
program type safe is in general undecidable.

As opposed to this, the dynamic type systems will not reject those
programs which are type safe but not proven so by the type checker,
because the type check is not applied until runtime.
This is one of the advantages of applying a dynamic type systems
to a language. On the contrary this type system has the disadvantages
that it will cause an increase in the runtime of the application.

A Soft type system is an attempt to combine the best of both
worlds. That is, to maintain the efficiency of applying the type check
at compile time and yet avoid the situation in which well typed
programs get rejected by the type checker. This is done by making as
much of the type check at compile time as possible, and leave the rest
- if any - to be done at runtime. By the rest, in this case, is meant
the parts of the program that cannot be decided to definitely type


Fri, 04 Jun 2004 18:51:09 GMT  
 [ 3 post ] 

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