General pattern bindings

[Malcolm Wallace]

Twan van Laarhoven <twanvl at gmail.com> wrote:

>  > The general form of a pattern binding is p match, where a match is
>  > the same structure as for function bindings above; in other words,
>  > a pattern binding is:
>  >
>  > p 	| g1 	= e1
>  >	| g2 	= e2
>  >	...
>  >	| gm 	= em
>  >	where { decls }
> 
> I did not even know these things existed, is there anyone who actually
> uses general pattern bindings?

It is worth mentioning that such pattern bindings are not only used at
the top-level - they are also valid in local definitions, where the
guards may involve variables bound at an outer scope.  This makes them
highly useful.

Regards,
    Malcolm