<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Feb 21, 2018, at 10:59 AM, Simon Peyton Jones <<a href="mailto:simonpj@microsoft.com" class="">simonpj@microsoft.com</a>> wrote:</div><div class=""><div class="WordSection1" style="page: WordSection1; font-family: Helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 11pt;" class=""> </span></div><p class="MsoListParagraph" style="margin: 0cm 0cm 6pt 72pt; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -17.85pt;"><span class=""><span class="">4.<span style="font-style: normal; font-variant-caps: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman';" class=""> <span class="Apple-converted-space"> </span></span></span></span><span class="">Define Type as a new<span class="Apple-converted-space"> </span><b class="">keyword</b><span class="Apple-converted-space"> </span>(with TypeInType). It does not need to be imported; it cannot be overridden or redefined. (Just like (->).) <o:p class=""></o:p></span></p><ul type="disc" style="margin-bottom: 0cm; margin-top: 0cm;" class=""><ol start="4" type="1" style="margin-bottom: 0cm; margin-top: 0cm;" class=""><ul type="square" style="margin-bottom: 0cm; margin-top: 0cm;" class=""><li class="MsoListParagraph" style="margin: 6pt 0cm; font-size: 11pt; font-family: Calibri, sans-serif;"><span class="">A variant of this (which I quite like) is to use the existing keyword<span class="Apple-converted-space"> </span><b class="">type</b><span class="Apple-converted-space"> </span>(lowercase).<o:p class=""></o:p></span></li><li class="MsoListParagraph" style="margin: 6pt 0cm; font-size: 11pt; font-family: Calibri, sans-serif;"><span class="">Advantage: simple clear story<o:p class=""></o:p></span></li><li class="MsoListParagraph" style="margin: 6pt 0cm; font-size: 11pt; font-family: Calibri, sans-serif;"><span class="">Note: won’t break existing code; only code that says TypeInType<o:p class=""></o:p></span></li></ul></ol></ul><p class="MsoNormal" style="margin: 0cm 0cm 6pt; font-size: 11pt; font-family: Calibri, sans-serif;"></p></div></div></blockquote><div><br class=""></div><div>The overall proposal still would break existing code, because -XTypeOperators would now mean that * is not available. That code would have to switch to using the new syntax, whatever it may be.</div><div><br class=""></div><div>Note that we can't really accept this proposal without figuring out what to do about *. Right now, -XTypeInType forces you to import Data.Kind to mention *. This is so that -XTypeInType code can also use type-level multiplication. If we merge -XTypeInType with -XPolyKinds (as proposed), then we need to resolve what will happen to existing code with -XPolyKinds and -XTypeOperators.</div></div><br class=""><div class="">Richard</div></body></html>