<div dir="ltr">also a longer thesis (which I believe is the backtracking optimization they refer to in the paper) is at <a href="http://publications.lib.chalmers.se/records/fulltext/157525.pdf">http://publications.lib.chalmers.se/records/fulltext/157525.pdf</a><div>I'll have to play with a very small language and see where I get.</div><div>Thanks to everybody, and if there're other examples around I'll be glad to know about them.</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Feb 17, 2015 at 3:15 AM, Paul Brauner <span dir="ltr"><<a href="mailto:polux2001@gmail.com" target="_blank">polux2001@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><p dir="ltr">There's a recent paper by Jonas Duregård et al where they introduce a variant of feat that allows for efficient discarding of unwanted values, à la lazy Smallcheck. The motivating example of the paper is exactly what you're looking for: discarding ill-formed programs.</p><div class="HOEnZb"><div class="h5">
<br><div class="gmail_quote">On Mon, Feb 16, 2015, 19:44 Andrey Chudnov <<a href="mailto:achudnov@gmail.com" target="_blank">achudnov@gmail.com</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
If you just need an example for generating and shrinking arbitrary
ASTs, you can have a look here:
<a href="https://github.com/jswebtools/language-ecmascript/blob/master/src/Language/ECMAScript3/Syntax/Arbitrary.hs" target="_blank">https://github.com/jswebtools/language-ecmascript/blob/master/src/Language/ECMAScript3/Syntax/Arbitrary.hs</a>
. Note that I use the testing-feat package to generate Gen instances
--- it tends to do better (explore interesting cases earlier) than
handwritten code --- and then fix-up incorrect ASTs (another option
is to simply discard them).</div><div bgcolor="#FFFFFF" text="#000000"><br>
<br>
<div>On 02/16/2015 12:33 PM, Maurizio Vitale
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">By 'test size reduction' I mean the 'shrink'
function. It seems to me (as I said, first Haskell program and
no experience with quickcheck) that it works nicely with a
topdown generation of the test, but I don't see how to easily
generate correct programs that way.
<div><br>
</div>
<div>Even if you cannot release your tests, maybe you can help
me with a very simple case. Consider a trivial AST. A program
is a possibly nested block. Each block is a bunch of
declarations of variables and some use of them</div>
<div><br>
</div>
<blockquote style="margin:0 0 0 40px;border:none;padding:0px">
<div>
<div>data Block = Block [Declaration] [Statement]</div>
</div>
<div>
<div><br>
</div>
</div>
<div>
<div>data Declaration = Var String String</div>
</div>
<div>
<div><br>
</div>
</div>
<div>
<div>data Statement = Statement Block | Use String</div>
</div>
</blockquote>
<div><br>
</div>
<div>How one would generate things like:</div>
<div><br>
</div>
<blockquote style="margin:0 0 0 40px;border:none;padding:0px">
<div>Block [Var "a" "int"] [Use "a"] -- here a is declared in
the same block</div>
<div><br>
</div>
<div>Block [] [Statement Block [Var "s" "int"] [Statement
Block [] [Use "s"]]] -- here s is declared in some other
visible scope</div>
</blockquote>
<div><br>
</div>
<div>etc.</div>
<div><br>
</div>
<div>Or am I trying to approach the problem from the wrong
angle?</div>
<div><br>
</div>
<div> </div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Feb 16, 2015 at 12:02 PM,
Andrey Chudnov <span dir="ltr"><<a href="mailto:achudnov@gmail.com" target="_blank">achudnov@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 bgcolor="#FFFFFF" text="#000000"> I use QuichCheck for
compiler testing where I generate random, but well-formed
programs and check some high-level syntactic properties on
results. The QuickCheck instance is open-source (see
language-ecmascript), but the compiler-test code is
closed-source at this time. Still, I found that it's not
the ultimate answer: many properties are hard to
formalize, so I have to resort to unit tests. I'm not sure
what you mean by "how this would play with test size
reduction". I think it's worth giving a try, but keep in
mind that you might still need to use unit tests.<br>
<br>
Let me know if you have any questions.<br>
<br>
/Andrey
<div>
<div><br>
<br>
<div>On 02/16/2015 11:53 AM, Maurizio Vitale wrote:<br>
</div>
</div>
</div>
<blockquote type="cite">
<div>
<div>
<div dir="ltr">I'm starting to work on my first real
haskell program (I've only RWH exercises under my
belt) and wondering whether people use quickcheck
at all for compiler testing.
<div><br>
</div>
<div>I've seen uses of quickcheck for testing
parsers, but I'm interested in generating
well-formed programs (e.g. random programs with
all declarations in reasonable random places).
This could be used to test passes other than
parsing (or even parsing, for languages that
needs to distinguish identifiers, like the
'typedef' problem in C/C++).</div>
<div><br>
</div>
<div>The only thing I can think of, is to use
quickcheck for randomly generating statements,
go over them and figure out free variables
(incl. functions) and generate declarations in
random places for them. But I'm not sure how
this would play with test size reduction and
doesn't look like a nice solution anyhow.</div>
<div><br>
</div>
<div>Any idea or pointers to examples? or should I
give up on quickcheck for this and just do
direct testing?</div>
<div><br>
</div>
<div>Thanks,</div>
<div><br>
</div>
<div> Maurizio</div>
</div>
<br>
<fieldset></fieldset>
<br>
</div>
</div>
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