<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div><blockquote type="cite" class=""><div style="font-family: Helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">One rationale I heard (I think from Ben Cohen) for why 'first' is <i class="">not</i> defined on Collection is that Sequences can be single-pass, and it would feel weird for a seemingly innocuous property like 'first' to have side effects.</div></blockquote></div><br class=""><div class="">This should be "<i class="">not</i> defined on Sequence", of course. Apologies for making the same mistake I was pointing out.</div></body></html>