Thanks Pierpaolo, I did not know about that useful trick with call-with-values, missed it sometimes.
Ryan, thanks! in-values-sequence did the trick perfectly. Regards, Dmitry On 02/05/2013 09:17 PM, Ryan Culpepper wrote:
On 02/05/2013 11:57 AM, Dmitry Pavlov wrote:Hello, Suppose I have the following code: (define conn (sqlite3-connect #:database "mydb.db" )) (for (((x y) (in-query c "SELECT X, Y FROM DATA"))) (displayln x) (displayln y)) in-query returns a sequence that gives two values at one call, and the "for" loop binds those values to x and y respectively, and everything works fine. Suppose then that I use an SELECT statement instrumented in runtime, and that I do not know beforehand how many values am I selecting. How do I get a list or a vector of my values per each row? It seems that I can not bind unknown number of values in a "for" loop, can I? Ideally, I would like a sequence that returns a list (or a vector) of column values at each call. query-row is close to what I need, but it can be used only if I have only one row, so no sequence. Any hints will be much appreciated.I think you want 'query-rows' (plural), which produces a list of vectors. If you want the cursor behavior of 'in-query', you could also try wrapping the 'in-query' sequence with 'in-values-sequence'. Ryan ____________________ Racket Users list: http://lists.racket-lang.org/users
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