<div dir="ltr"><div>Ah, thanks Anton!</div>But wouldn't/couldn't things be different if tuples was written with eg<span style="font-size:13px"> ⊂⊃ instead of parentheses?</span><div>(let's ignore the practical implications (difficult to write etc) for the moment)</div><div><br></div><div>For example, here's an optional tuple whose single element is a function:</div><div><div><span style="font-size:13px">⊂Int -> Int⊃? </span></div><div><br></div><div>and here is an optional function:</div><div>(Int -> Int)?</div><div><br></div><div>In this thought-experiment, parentheses are _only_ used for grouping (setting priorities), and they are the only grouping which is sloppy/forgiving, so this would also be an optional tuple whose single element is a function:</div><div><br></div><div><span style="font-size:13px">((((((((⊂Int -> Int⊃))))))?))</span><br></div><div><br></div><div>But this would be an optional tuple whose single element is a single element tuple whose single element is a function:</div><div><span style="font-size:13px">⊂</span><span style="font-size:13px">⊂Int -> Int</span><span style="font-size:13px">⊃</span><span style="font-size:13px">⊃</span><span style="font-size:13px">? </span></div><div><br></div><div>/Jens</div><div><div><span style="font-size:13px"><br></span></div></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Jul 6, 2016 at 12:23 PM, Anton Zhilin <span dir="ltr"><<a href="mailto:antonyzhilin@gmail.com" target="_blank">antonyzhilin@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 dir="ltr"><span class=""><span style="font-size:12.8px">> Or maybe I have just forgotten the reasons for why there can be no such thing as (a nested) single element tuple (type).</span></span><div><span style="font-size:12.8px"><br></span><div class="gmail_extra"><div class="gmail_quote">In Swift, types have their own (built-in) operators: infix '->', postfix '?', postfix '!'.</div><div class="gmail_quote">Parentheses are required for grouping (setting priorities). If we allow single element tuples, ambiguities arise:</div><div class="gmail_quote"><br></div><div class="gmail_quote">(Int -> Int)? // is that an optional tuple or just optional function?</div><div class="gmail_quote"><br></div><div class="gmail_quote">By the way, in Haskell, which allows user-defined operators on types, there is no single element tuple for pretty much the same reason.</div></div></div></div>
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