[r6rs-discuss] Scheme pattern matching & R*RS

[John Cowan]

Per Bothner scripsit:

> I.e. where (var1 var2 var3) is a valid pattern matching a 3-element list.
> This syntax for patterns has the advantage that it is a generalization of
> syntax-rules patterns, in addition to being natural and compact.

Ah, I see.  I think that the natural extension of define is to allow it
to define a single named pattern-matching procedure rather than allowing
it to define multiple names simultaneously.

> In that case, how do you distinguish:
>
>   (define (function-name param1 param2) <expression>)
>
> from
>
>   (define (var1 var2 var3) <expression>)

The former is the only meaning, but with pattern-matching define
you may also write (define (foo (v1 v2) v3) ...) to define
a procedure which accepts two arguments, the first of which is a
two-element list.

-- 
John Cowan      cowan at ccil.org
        "Not to know The Smiths is not to know K.X.U."  --K.X.U.