<div dir="ltr">What you posted is the format for data declarations, not newtypes. Newtypes are required to have exactly one constructor: <table cellspacing="0" style="font-family:Times"><tbody><tr><td><tt><br class="">newtype</tt> [context <tt>=></tt>] simpletype <tt>=</tt> newconstr [deriving]<br><br></td></tr></tbody></table><br><div>Adam</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Aug 12, 2016 at 4:43 PM, James Brown <span dir="ltr"><<a href="mailto:james.brown5374@gmail.com" target="_blank">james.brown5374@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><span style="font-family:Arial,Helvetica,sans-serif;font-size:13px">In the Haskell report 2010, a data declaration has the format of:</span><p style="margin:1em 0px;padding:0px;border:0px;font-family:Arial,Helvetica,sans-serif;font-size:13px;clear:both"><a href="https://lh3.googleusercontent.com/-G-z92n-50B0/V63XKCCrJDI/AAAAAAAAAGA/w-Zdi9DaR18hX67n-OeQNkDB1iUR0IP7gCLcB/s1600/Screen%2BShot%2B2016-08-12%2Bat%2B10.03.00%2BAM.png" rel="nofollow" style="margin:0px 1em;padding:0px;border:0px;text-decoration:none;color:rgb(102,17,204)" target="_blank"><img src="https://lh3.googleusercontent.com/-G-z92n-50B0/V63XKCCrJDI/AAAAAAAAAGA/w-Zdi9DaR18hX67n-OeQNkDB1iUR0IP7gCLcB/s320/Screen%2BShot%2B2016-08-12%2Bat%2B10.03.00%2BAM.png" border="0" width="320" height="25" style="margin:0px;padding:0px;border:0px"></a></p><p style="margin:1em 0px;padding:0px;border:0px;font-family:Arial,Helvetica,sans-serif;font-size:13px;clear:both">For a new type, there could be zero or more data constructors. What's the use case for a new type that has zero data constructor? </p></div>
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