Not sure what you want...
I find this description of "procedure?" at
https://www.cs.cmu.edu/Groups/AI/html/r4rs/r4rs_8.html
essential procedure: procedure? obj
Returns #t if obj is a procedure, otherwise returns #f.
(procedure? car) => #t
(procedure? 'car) => #f
(procedure? (lambda (x) (* x x)))
=> #t
(procedure? '(lambda (x) (* x x)))
=> #f
(call-with-current-continuation procedure?)
=> #t
The J "foreign" 4!:0 returns the part of speech of a boxed string, or
set of boxed strings.
I happen to have a verb "rep" and a noun "q" in my session. So:
4!:0 'rep';'q'
3 0
So we can test if names are names of verbs: (fixed width font best here)
(3 = 4!:0 @< ) each ;:'rep q'
┌─┬─┐
│1│0│
└─┴─┘
So this simple illustrative function MIGHT be useful - there are tacit
ways to do the same thing -
procquery =: 3 : 0
obj =. y
if. (3 = 4!:0 @{.@;: ) obj do.
". obj
else.
'false'
end.
)
with these results on my verb rep and noun q:
procquery 'rep 2 7' NB. period of repeating decimal 2/7
6
procquery 'q 2 7' NB. meaningless...
false
I see Raul has just posted too. Should be more useful...
Cheers,
Mike
On 16/01/2020 19:55, Raoul Schorer wrote:
Hi,
I am translating scheme code that makes heavy use of delayed evaluation
(thunks). In scheme, there is a predicate 'procedure?' that returns a
boolean. I translated that into a check for a boxed string, which is the
representation I use for delayed procedures, which I then 'force' using ".@>
1. Is there a better way than building a program string to get delayed
eval? I tried using (3: '(delayed_verb)"_'), but the interpreter seems to
greedily eval the whole thing with that pattern. The only working solution
I found was to convert everything to string.
2. Is there a general test similar to 'procedure?' in J?
Thanks!
Raoul
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