<div dir="ltr"><div>On Wed, Jul 11, 2012 at 7:27 PM, Johan Tibell <span dir="ltr"><<a href="mailto:johan.tibell@gmail.com" target="_blank">johan.tibell@gmail.com</a>></span> wrote:</div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="im">For example, most functions in bytestring are unsafe because their</div>
implementation uses unsafePerformIO. To be very concrete, if 'map' on<br>
ByteStrings is unsafe it needs to be moved from<br></blockquote><div><br></div><div>While I share your distrust of the whole Safe Haskell movement as being a lot of effort for an unproven benefit from a definition of "safe" that is not demonstrated to be of practical usefulness or practical concern, I think you're wrong here.</div>
<div><br></div><div>unsafePerformIO is unsafe.</div><div><br></div><div>Data.ByteString.map is only unsafe if it allows unsafePerformIO to be abused.</div><div><br></div><div>If it can verify that nothing actually unsafe takes place — which it does, by dint of the promise inherent in it being exposed as pure — Data.ByteString.map is *not* unsafe. The mechanical application of "oh, it uses unsafePerformIO, we don't care whether it proves it has used it safely: it must by definition be unsafe" just complicates things even more. If indeed it's not simply a strawman.</div>
<div><br></div></div>-- <br>brandon s allbery <a href="mailto:allbery.b@gmail.com" target="_blank">allbery.b@gmail.com</a><br>wandering unix systems administrator (available) (412) 475-9364 vm/sms<br>
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