How about a PDCO :-
procedure nth_result(a)
local n
n := integer(@a[1]) | fail
every 1 to n - 1 do
@a[2] | fail
return @a[2]
end
procedure main()
write( nth_result { 3, "a"|"b"|"c"|"d" } )
end
Here nth_result { n, expr } will produce the nth result from
expr, or fail.
Art Eschenlauer wrote:
>
> Is there a compact way to reference the Nth result in the set of results
> produced?
>
> For example, suppose that I want to obtain the third result produced by
> the expression ("a"|"b"|"c"|"d"). Thinking in my stone-age procedural way,
> I would write:
>
> procedure main()
> i := 0
> every s := ("a"|"b"|"c"|"d") do {
> write ("s = "||s)
> i +:= 1
> if i = 3 then {
> write ("i = "||i)
> write(s)
> break
> }
> }
> end
>
> I suppose that I could do this with a co-expression:
>
> procedure main()
> E := create ("a"|"b"|"c"|"d")
> i := 0
> while s := ! @E do {
> write ("s = "||s)
> i +:= 1
> if i = 3 then {
> write ("i = "||i)
> write(s)
> break
> }
> }
> end
>
> but I don't think that immediately gives me much benefit.
>
> What I'm hoping for is a compact syntax, similar to one of the following
> examples except that it would actually work!
> ("a"|"b"|"c"|"d")[3]
> 3("a"|"b"|"c"|"d")
>
> The most compact idiom I have come up with is:
> every s := ("a"|"b"|"c"|"d")\3 ; write (s)
> Any suggestions?
> Is there an idiomatic way to get rid of the variable s for example?
>
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