5 FAQ

5.1 Why simple-xlsx’writer is so slow when I have much more rows?

No, simple-xlsx’s write is not slow(not so fast, perhaps).

If you find it turns slow when you have much rows, it perhaphs you prepare rows like below:

(let ([rows '()])

(set! rows `(,@rows ,row))

or (set! rows (append rows row)))

When rows’s count is small, its ok, but when you have thousands rows, it’s getting too slow to complete.

When work on big data, you should do like this:

(let loop ([rows '()]

[line (read-line)])

(if (not (eof-object? line))

(loop (cons (list (regexp-replace* #rx"\n|\r" line "")) rows) (read-line) (add1 count)))

(send xlsx add-sheet (reverse rows) "Sheet1"))

Please notice you should use reverse list order when use cons to chain a list up.