Hi Edward, hello to all list members,<div>thank you for your comments, I will keep that in mind. There will be operations on matrices (and other objects) which modify the objects,</div><div>and those will be in IO or ST, I think.</div>
<div>However, I am planning to provide operations with matrices which guarantee that each involved matrix is not changed, but which may return new matrices.</div><div>All matrices have to be allocated, and that allocation can fail ... how does one usually go about this problem in Haskell?</div>
<div><br></div><div>Cheers,</div><div>Christian</div><div><br><br><div class="gmail_quote">2011/2/9 Edward Z. Yang <span dir="ltr">&lt;<a href="mailto:ezyang@mit.edu">ezyang@mit.edu</a>&gt;</span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Hello Christian,<br>
<br>
Assuming that the foreign library is based off of mutation on matrices,<br>
there&#39;s not an easy way to export a nice pure interface to them, because<br>
they&#39;re not actually persistent: if another thread goes and modifies<br>
some pointer which you also have in pure code, referential transparency<br>
is broken.  So you&#39;ll have to think carefully about what sorts of guarantees<br>
you can (or want) to make to Haskell, and if you can&#39;t fulfill them, keep<br>
the code in IO (or create your own monad for manipulating matrices).<br>
<font color="#888888"><br>
Edward<br>
</font></blockquote></div><br></div>