<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=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Sep 7, 2020, at 8:04 AM, Tom Ellis <<a href="mailto:tom-lists-haskell-cafe-2017@jaguarpaw.co.uk" class="">tom-lists-haskell-cafe-2017@jaguarpaw.co.uk</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 11px; 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="">On the</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 11px; 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;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 11px; 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="">other hand I'm still somewhat concerned that the meaning of the syntax</span><br style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 11px; 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;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 11px; 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="">can vary depending on whether the type variable is in scope or not.</span></div></blockquote></div><br class=""><div class="">Yes. This has been a spot of discomfort for some time (at least for me, and I know I'm not completely alone).</div><div class=""><br class=""></div><div class="">A recent accepted, unimplemented proposal (<a href="https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0285-no-implicit-binds.rst" class="">https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0285-no-implicit-binds.rst</a>) describes -XNoPatternSignatureBinds, which disallows not-in-scope variables from appearing in pattern signatures. Instead, the variable must come into scope some other way. That "other way" depends on proposals not yet completely formed/accepted, but once the dust has settled, I think you'll get what you want with -XNoPatternSignatureBinds.</div><div class=""><br class=""></div><div class="">Richard</div></body></html>