On Sat, Jul 24, 2010 at 11:45 AM, Mark Engelberg <mark.engelb...@gmail.com> wrote: > The simplest translation is to wrap a lazy-seq around the last line to > avoid the stack overflows.
Just to clarify, there are at least three reasonable places to place the call to lazy-seq. You can put lazy-seq around the full body of the function. You can place it around the cons. You can place it around the recursive call to scheme-remove-first. Each choice results in slightly different laziness behavior, i.e., when various elements are computed, but the overall semantics of the sequence remains the same and stack overflows will be avoided. Placing the lazy-seq around the recursive function call will cause scheme-remove-first to compute the first element right away, and delay the rest. Placing the lazy-seq around the full body will prevent any computation until it is asked for by a consumer. Placing the lazy-seq around the cons results in in immediate behavior for the nil and removable-item-at-front-of-list case, and delayed behavior otherwise. All are acceptable choices, but preferences vary. Probably placing lazy-seq around the full body is the most common style you'll see in Clojure, although I tend to place it where the laziness is actually required (like around the recursive call, or around the cons). You've probably noticed from the other samples posted that many Clojurians prefer to use (seq lst) instead of (not (empty? lst)), and organize their code around the not-empty case. So (if (empty? lst) empty-case not-empty-case) becomes (if (seq lst) not-empty-case empty-case) When the empty case also results in nil, you can replace the if structure with a one-armed when, because when automatically returns nil in the other case. So (if (seq lst) not-empty-case nil) becomes (when (seq lst) not-empty-case). -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
