Re: Free variables in Curry

From: Herbert Kuchen <kuchen_at_uni-muenster.de>
Date: Thu, 07 Jan 1999 13:34:11 +0000

> > My conclusion is that the use of undeclared free variables should
> > be banned from the language. These would be the only elements of
> > the language making an exception to the rule that identifiers must
> > be declared. Although undeclaring free variables eases
> > understanding in simple situations where understanding is already
> > easy, this practice makes understanding more difficult in other
> > situations where understanding is difficult. Hence it is not a
> > beneficial feature.
>
> I agree on this. Looking at my Curry programs, free variables
> only occur at some few places in the program text (due to the use
> of functions; in logic programming free variables are extensively
> used to pass results from one predicate to another which is
> not necessary in Curry) and for most of these occurrences it
> is already clearer to define them explicitly. Furthermore,
> the explicit definition of existential variables is also
> required in other programming languages with different scopes.
>
> Thus, the proposal is to omit the possibility to use undeclared
> free variables. This makes the language simpler but requires
> more writing in some situations.
>
> Any objections?

I support this change,

Herbert
Received on Thu Jan 07 1999 - 13:42:00 CET

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