On 12/14/2010 01:58 PM, Jim Wise wrote:
> what else should I be looking at? What other scheme implementations
> provide pattern matching support?
There is SRFI 16's case-lambda, but it's pretty simple.
SRFI 51's rest-values is also relevant.
I'd like the syntax for lambda to be:
(lambda <pattern> <body>)
That means that if R7RS supports optional arguments then the following
(or something functionally equivalent) should be a valid <pattern>:
(a b #!optional c (d 10))
or even:
((a b #!optional c) #!optional (d #f))
This matches either a 1- or a 2-element list, where the first car
most be a 2- or a 3-element list.
Not that such functionality is required for R7RS - just that we should
keep in mind that a "list-pattern" is not just a "list of patterns".
Also, a question to ponder: For implementations that provide some kind of
abstract "sequence" type that is (at least) a superset of both list and
vector:
They might want to allow a list pattern to match either a sequence or
vector.
Not perhaps directly relevant to R7RS standardization, unless we're
considering
abstract sequences types for R7RS, but note that is a direction some of us
might like to move towards.
--
--Per Bothner
[email protected] http://per.bothner.com/
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