Re: [stack] sweetening concatenative syntax

On Mar 6, 2008, at 4:49 PM, William Tanksley, Jr wrote:

> John Nowak <[email protected]> wrote:
>> William Tanksley, Jr wrote:
>>> But in no case does this functionality REQUIRE
>>> lambdas or locals; why should it? All you're doing is  
>>> patternmatching.
>
>> I'm actively trying to avoid defining the language in terms of  
>> pattern
>> matching. Here, 'unlist' is just a normal function. But yes, of  
>> course
>> it doesn't require locals. You could do this as well:
>>    map = swap
>>          []
>>          [rot dup 2keep swap map cons]
>>        unlist
>
> ...but you're still doing patternmatching. Aren't you? What am I  
> missing?

'unlist' is just a normal function that gets defined as a result of  
declaring the 'list' data type:

    unlist :: A {b} [A -> C] [A b {b} -> C] -> C

This is different from general pattern matching as there's no way to  
match on particular values and "matching" here is guaranteed to be  
constant time. Alternatively, it isn't pattern matching as it doesn't  
involve patterns. The fact that it *looks* like pattern matching when  
lambda expressions are used is a very nice thing.

>

- John