> 1) having a list and then using for-each it to display the commit 
> information;
> 2) display the list while building it.

Would something like list-transduce from srfi-171 be useful?
list-transduce lets you avoid building intermediate lists that need to
be garbage collected.

https://www.gnu.org/software/guile/manual/html_node/SRFI_002d171.html