Hmm, interesting. I might be tempted to use a 40-bit type for large arrays, but the performance hit for any useful computation over a large array would probably tilt heavily in favor of plain 64-bit integers. What's your use case for such a 40-bit type? And is it common enough to justify such a facility in the stdlib vs. providing the tools to build it yourself?<br><br><div class="gmail_quote"><div dir="ltr">On Sun, Jan 29, 2017 at 12:29 David Sweeris via swift-evolution <<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto" class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">On Jan 13, 2017, at 12:47, Max Moiseev via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="gmail_msg" target="_blank">swift-evolution@swift.org</a>> wrote:<br class="gmail_msg"><br class="gmail_msg"><span style="font-size:1.25em;color:rgb(51,51,51);font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Helvetica,Arial,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';background-color:rgb(255,255,255)" class="gmail_msg">DoubleWidth</span></div></div><div dir="auto" class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg"><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Helvetica,Arial,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px;background-color:rgb(255,255,255)" class="gmail_msg">The <code style="box-sizing:border-box;font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:13.600000381469727px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px" class="gmail_msg">DoubleWidth<T></code> type allows to create wider fixed-width integer types from the ones available in the standard library.</p></div></blockquote></div><div dir="auto" class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg"><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Helvetica,Arial,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px;background-color:rgb(255,255,255)" class="gmail_msg">Standard library currently provides fixed-width integer types of up to 64 bits. A value of <code style="box-sizing:border-box;font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:13.600000381469727px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px" class="gmail_msg">DoubleWidth<Int64></code> will double the range of the underlying type and implement all the <code style="box-sizing:border-box;font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:13.600000381469727px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px" class="gmail_msg">FixedWidthInteger</code> requirements. <em style="box-sizing:border-box" class="gmail_msg">Please note</em> though that the implementation will not necessarily be the most efficient one, so it would not be a good idea to use <code style="box-sizing:border-box;font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:13.600000381469727px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px" class="gmail_msg">DoubleWidth<Int32></code>instead of a built-in <code style="box-sizing:border-box;font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:13.600000381469727px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px" class="gmail_msg">Int64</code>.</p></div></blockquote><br class="gmail_msg"><div class="gmail_msg">What about having a "<span style="background-color:rgba(255,255,255,0)" class="gmail_msg">CompoundBinaryInteger</span><T,U>" type, and then do "typealias DoubleWidth<T> = CompoundBinaryInteger<T,T>"? That would make it easier to have, say, 40-bit ints, "<span style="background-color:rgba(255,255,255,0)" class="gmail_msg">CompoundBinaryInteger<Int8,Int32>", while still having the convenience of "DoubleWidth<T>".</span></div><div class="gmail_msg"><span style="background-color:rgba(255,255,255,0)" class="gmail_msg"><br class="gmail_msg"></span></div><div class="gmail_msg"><span style="background-color:rgba(255,255,255,0)" class="gmail_msg">- Dave Sweeris</span></div></div>_______________________________________________<br class="gmail_msg">
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