<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="">Because it works by increasing size, yes, it doesn’t need guidance about the order. On the other hand, you’re exploring a different part of the space of possible inputs. There’s also Lazy SmallCheck, too.<div class=""><br class=""></div><div class="">Which is best? There’s no clear answer to this, but a reasonable principle is to try a bundle of approaches if you want to argue that you have used a limited amount of testing resource in as prudent as possible a way.</div><div class=""><br class=""></div><div class="">Simon<br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 17 Jun 2018, at 11:28, Oliver Charles <<a href="mailto:ollie@ocharles.org.uk" class="">ollie@ocharles.org.uk</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">Is SmallCheck more principled in this regard, or would people consider that equally hacky?<br class=""><br class=""><div class="gmail_quote"><div dir="ltr" class="">On Sun, 17 Jun 2018, 10:18 am Petr Pudlák, <<a href="mailto:petr.mvd@gmail.com" class="">petr.mvd@gmail.com</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="">PS: Just to make clear, it's not that I have something against QuickCheck or similar libraries, on the contrary, they're great! I'm just playing the devil's advocate to analyze and understand the concept.</div><br class=""><div class="gmail_quote"><div dir="ltr" class="">ne 17. 6. 2018 v 4:05 odesílatel Oleg Grenrus <<a href="mailto:oleg.grenrus@iki.fi" target="_blank" class="">oleg.grenrus@iki.fi</a>> napsal:<br class=""></div></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto" class=""><div class=""><div style="direction:inherit" class=""><div style="direction:inherit" class=""><span style="background-color:rgba(255,255,255,0)" class="">Not only avoid extremely large trees, but in general guarantee termination of the generation process</span></div></div><br class="">Sent from my iPhone</div></div><div dir="auto" class=""><div class=""><br class="">On 15 Jun 2018, at 0.31, David Feuer <<a href="mailto:david.feuer@gmail.com" target="_blank" class="">david.feuer@gmail.com</a>> wrote:<br class=""><br class=""></div><blockquote type="cite" class=""><div class=""><div dir="auto" class=""><div dir="auto" class="">data Foo a = Leaf a | Node [Foo a]</div><div dir="auto" class=""><br class=""></div>Without the size parameter, it's a bit tricky to control the distribution to avoid generating extremely large trees. I certainly agree, however, that the size parameter is an ugly and ill-specified hack.</div><br class=""><div class="gmail_quote"><div dir="ltr" class="">On Thu, Jun 14, 2018, 4:20 PM Petr Pudlák <<a href="mailto:petr.mvd@gmail.com" target="_blank" class="">petr.mvd@gmail.com</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="">Hi everyone,<div class=""><br class=""></div><div class="">I'd like to better understand the principles behind the 'size' parameter. Looking at quickCheckWithResult [1], its computation seems to be somewhat non-trivial, or even arbitrary. As far as I understand it, the size is varied throughout tests, increasing from small to larger values. I see two main purposes:</div><div class=""><br class=""></div><div class="">- Test on smaller as well as larger values. But with generators having proper distribution of values, this should happen anyway, just as if we had a constant, larger 'size' parameter.</div><div class="">- Starting with smaller sizes allows to find smaller count-examples first. But with shrinking, it doesn't matter that much, big counter-examples are shrunk to smaller ones anyway in most cases.</div><div class=""><br class=""></div><div class="">So is this parameter actually necessary? Would anything change considerably if it was dropped?</div><div class=""><br class=""></div><div class="">Thanks,</div><div class="">Petr</div><div class=""><br class=""></div><div class="">[1] <a href="http://hackage.haskell.org/package/QuickCheck-2.11.3/docs/src/Test-QuickCheck-Test.html#quickCheckWithResult" rel="noreferrer" target="_blank" class="">http://hackage.haskell.org/package/QuickCheck-2.11.3/docs/src/Test-QuickCheck-Test.html#quickCheckWithResult</a></div></div>
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<div class=""><span style="font-family: LucidaGrande;" class="">Simon Thompson | Professor of Logic and Computation </span><br style="font-family: LucidaGrande;" class=""><span style="font-family: LucidaGrande;" class="">School of Computing | University of Kent | Canterbury, CT2 7NF, UK</span><br style="font-family: LucidaGrande;" class=""><a href="mailto:s.j.thompson@kent.ac.uk" style="font-family: LucidaGrande;" class="">s.j.thompson@kent.ac.uk</a><span style="font-family: LucidaGrande;" class=""> | M +44 7986 085754 | W </span><a href="http://www.cs.kent.ac.uk/~sjt" style="font-family: LucidaGrande;" class="">www.cs.kent.ac.uk/~sjt</a></div>
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