<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Aug 31, 2020, at 10:34 AM, Spiwack, Arnaud <<a href="mailto:arnaud.spiwack@tweag.io" class="">arnaud.spiwack@tweag.io</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; 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; text-decoration: none; float: none; display: inline !important;" class="">That being said, Richard seemed to feel rather strongly about this one. Richard, do you still agree with your then position that<span class="Apple-converted-space"> </span></span><code style="caret-color: rgb(0, 0, 0); font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; font-size: 0.85em; font-family: Consolas, Inconsolata, Courier, monospace; margin: 0px 0.15em; padding: 0px 0.3em; white-space: pre-wrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; display: inline;" class="">let (#x, y#) = …</code><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; 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; text-decoration: none; float: none; display: inline !important;" class=""><span class="Apple-converted-space"> </span>being a lazy pattern (hence implicitly boxes the pair) is the right semantics?</span></div></blockquote></div><br class=""><div class="">I admit I don't feel as strongly any more. My argument in that thread was from the standpoint of a language designer: there is really no reason, a priori, for an unboxed-tuple binding to be strict. What controls strictness is whether the bound variables are of unlifted type. However, I'm currently in more sympathy with language users, who (for whatever reason) seem to think that bindings with #s in them should be strict. (I have this intuition myself, even though it's not quite warranted on technical grounds.)</div><div class=""><br class=""></div><div class="">What do we think of</div><div class=""><br class=""></div><div class=""><div class=""></div><blockquote type="cite" class=""><div class="">pattern Unl x y = (# x, y #)</div><div class=""><br class=""></div><div class="">ex1, ex2 :: ()</div><div class="">ex1 = let Unl x y = Unl undefined undefined in ()</div><div class="">ex2 = let Unl x y = undefined in ()</div></blockquote></div><div class=""><br class=""></div><div class="">? Today, both ex1 and ex2 evaluate to (). If we were to change the specification here, would we consider any unlifted-type pattern (where the type of the pattern itself is unlifted, independent of the type of any of its bound variables) to be banged? Or would it be a super-special case for unboxed tuples?</div><div class=""><br class=""></div><div class="">Richard</div></body></html>