Chris Dean wrote:

[1] The anatomy of a loop: a story of scope and control. Olin Shivers. http://www.cc.gatech.edu/~shivers/citations.html#loop

[2] Eager Comprehensions in Scheme: The design of SRFI-42 Sebastian Egner http://www.deinprogramm.de/scheme-2005/program.html

Thank you very much for these pointers. I'm very happy to see research in iteration in a way that is potentially useable for CL (unlike iteration constructs in many other languages). I'm still looking for the ideal construct myself. :-)

This is my standard looping question in any language: Read the last N lines of a file, transform them, filter them, and return the unique elements.

Not trivial, even with SRFI-42.

It's interesting how Iterate and SRFI-42 appear somewhat inside-out: one has COLLECT buried somewhere inside the body, the other right upfront (list-ec). OTOH, one has the form to be collected buried deep inside, the other right next to COLLECT. Good reading.

Regards, Jorg Hohle