<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><blockquote type="cite"><div class="gmail_quote"><div><div>What if you have another program, written in C or something, that monitors a file for changes, and if so changes the contents of another file? Surely to catch that you must mark *all* file system access as "interefering"? Even worse, another program could monitor the state of a file and conditionally disable thet network driver, now file access interferes with network access.</div></div></div></blockquote></div><div><br></div><div>A compiler or runtime system can't know about these kinds of things -- unless perhaps you push the effect system into the operating system (interesting idea). The best you can do is ensure the program itself is correct in the absence of interference from other programs, but there's no way to obtain a guarantee in the presence of interference. Either with an effect system, or without (think of all the sequential imperative code that gets broken when other programs concurrently tamper with the file system or networking, etc.).</div><div><br></div><div apple-content-edited="true"> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div>Regards,</div><div><br></div><div>John A. De Goes</div><div>N-Brain, Inc.</div><div>The Evolution of Collaboration</div><div><br></div><div><a href="http://www.n-brain.net">http://www.n-brain.net</a> | 877-376-2724 x 101</div></div></div></span></div></span></div></span></div></span></div></span> </div><br><div><div>On Aug 13, 2009, at 2:42 AM, Sebastian Sylvan wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><br><br> <div class="gmail_quote">On Thu, Aug 13, 2009 at 4:56 AM, John A. De Goes <span dir="ltr"><<a href="mailto:john@n-brain.net">john@n-brain.net</a>></span> wrote:<br> <blockquote style="border-left-color: rgb(204, 204, 204); border-left-width: 1px; border-left-style: solid; margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0.8ex; padding-left: 1ex; position: static; z-index: auto; " class="gmail_quote"><br>The next step is to distinguish between reading file A and reading file B,</blockquote> <blockquote style="border-left-color: rgb(204, 204, 204); border-left-width: 1px; border-left-style: solid; margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0.8ex; padding-left: 1ex; position: static; z-index: auto; " class="gmail_quote"><span></span>between reading file A and writing file A, between reading one part of file A and writing another part of file A, etc. When the effect system can carry that kind of information, and not just for files, but network, memory, etc., then you'll be able to do some extremely powerful parallelization & optimization.<br> </blockquote> <div> </div> <div> <div>What if you have another program, written in C or something, that monitors a file for changes, and if so changes the contents of another file? Surely to catch that you must mark *all* file system access as "interefering"? Even worse, another program could monitor the state of a file and conditionally disable thet network driver, now file access interferes with network access.</div> </div></div><br clear="all"> <div></div><br>-- <br>Sebastian Sylvan<br></blockquote></div><br></body></html>