Thanks Kip - I thought of using i. but I think the list would need to
be lazily evaluated to meet the 2nd part of the criteria of what I'm
looking for.
i. can be used to find the first match
ops=:(1 = #) , (2 = #) , (10 >:~ +/) , 100 >:~ +/
(c1 ` c2 ` c3 `c4 `c0) @. ((ops (1 2 300)) i. 1) ''
sum >= than 10
(c1 ` c2 ` c3 `c4 `c0) @. ((ops ('')) i. 1) ''
default
I assume ops is evaluated prior to matching. The concern is if the
logic checks have any side effects or are slow, then each one is
evaluated instead of stopping at the first one. Of course there are
ways to code the logic checks differently. In a traditional case
statement (for example a SQL case statement generally provides
deterministic short circuit evaluation), it would stop at the first
match
On Tue, Nov 5, 2013 at 9:51 AM, km <[email protected]> wrote:
> See the documentation for Index Of i.
>
> http://www.jsoftware.com/docs/help701/dictionary/didot.htm
>
> 1 2 3 4 i. 3 _3 NB. 1 2 3 4 index of 3 is 2; _3 not found
> 2 4
>
> --Kip Murray
>
> Sent from my iPad
>
>> On Nov 5, 2013, at 8:18 AM, Joe Bogner <[email protected]> wrote:
>>
>> I'm experimenting with Agenda and building a verb to return the index.
>>
>> My case verb generally does what I'd like, but I was stumped on how to
>> rework it so that it stops on the first match to work more like a
>> traditional case statement.
>>
>> If the conditions were mutually exclusive then I could use a + between
>> them - each would still process though. Since they aren't, I opted for
>> the largest of the matching index. Is there a clean way to say the
>> first non-zero or zero if no others match? What would be the idomatic
>> way to handle it?
>>
>> Also, ideally it wouldn't process the next statement if it finds a match.
>>
>> c0=:smoutput bind 'default'
>> c1=:smoutput bind 'only one'
>> c2=:smoutput bind 'two'
>> c3=:smoutput bind 'sum >= than 10'
>> c4=:smoutput bind 'sum >= than 100'
>> case=:(1*(1 = #)) >. (2*(2 = #)) >. (3*(10 >:~ +/)) >. (4*(100 >:~ +/))
>> dispatch=:(c0 ` c1 ` c2 ` c3 `c4) @. case
>>
>> dispatch 1
>> only one
>>
>> dispatch 2
>> only one
>>
>> dispatch 1 2
>> two
>>
>> dispatch 2 8
>> sum >= than 10
>>
>> dispatch 2 3 5
>> sum >= than 10
>>
>> dispatch 2 3 5 100
>> sum >= than 100
>> ----------------------------------------------------------------------
>> For information about J forums see http://www.jsoftware.com/forums.htm
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
