Hi, You might not need a tokenizer. Probably something like that should do it: (with-input-from-file "my-file.txt" #:mode 'text (lambda () (let loop ([numbers '()] [line (read-line)]) (if (eof-object? line) (reverse numbers) (loop (cons (filter (lambda(x)x) (map string->number (regexp-split #px"\\s+" line))) numbers) (read-line)))))) Lines are read one by one, and each line is split on spaces with regexp-split, then empty values are removed (with filter), strings are turned into numbers with string->number, and all the values are consed into a list of list of numbers. Hope this helps, Laurent <div class="gmail_quote">On Sun, Nov 8, 2009 at 08:41, <<a href="mailto:krhari@ccs.neu.edu">krhari@ccs.neu.edu</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Hi, I have a file which contains data like this 2.5500000e-002 3.6238983e-002 2.5500000e-002 3.6238638e-002 2.5500000e-002 3.6237603e-002 ... I am working on a small animation I need these numbers to calculate some things there... I am using 2htdp/universe teachpack... I actually found string->tokenize function in SRFI doc... Can I use it? If yes can anyone guide me how to use SRFI? If no is there any other way out other than converting the file into a string then using sting->list and doing it in brute force way? If I use file->string, I get a string like this " 2.5500000e-002 3.6238983e-002\r\n 2.5500000e-002 3.6238638e-002\r\n 2.5500000e-002 3.6237603e-002\r\n" Please help me out... Thanks Hari _________________________________________________ For list-related administrative tasks: <a href="http://list.cs.brown.edu/mailman/listinfo/plt-scheme" target="_blank">http://list.cs.brown.edu/mailman/listinfo/plt-scheme</a> </blockquote></div>