<div dir="ltr">On Sun, Dec 6, 2015 at 11:56 PM, Richard Eisenberg <span dir="ltr"><<a href="mailto:eir@cis.upenn.edu" target="_blank">eir@cis.upenn.edu</a>></span> wrote:<br><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="word-wrap:break-word"><div>That looks like exactly what I want. Thanks.</div><div><br></div><div>There remain two mysteries:</div><div>- I thought that CallStacks were a new feature that would come with GHC 8.0. Yet it seems the datatype is present in base-4.8.x. Even though the docs even say (wrongly, evidently) that it's in base since 4.9.</div></div></blockquote><div> <br></div><div>Somehow some CallStack-related things snuck in between 7.10.1 and 7.10.2. Compare <a href="https://hackage.haskell.org/package/base-4.8.0.0/docs/GHC-Stack.html">https://hackage.haskell.org/package/base-4.8.0.0/docs/GHC-Stack.html</a> and <a href="https://hackage.haskell.org/package/base-4.8.1.0/docs/GHC-Stack.html">https://hackage.haskell.org/package/base-4.8.1.0/docs/GHC-Stack.html</a>.<br><br></div><div>Regards,<br></div><div>Reid Barton<br></div></div></div></div>