Re: [NTG-context] Math literal colon

24 Jul 2015

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On 24 Jul 2015, at 11:40, Hans Hagen  wrote:
On 7/20/2015 6:09 PM, Hans Aberg wrote:
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On 20 Jul 2015, at 17:50, Manuel Blanco  wrote:
A little bit more of intelligence can be given with
\begingroup\lccode`\~=`\:\lowercase{\endgroup
     \unexpanded\def~}{\futurelet\tmptoken\docolon}
   \unexpanded\def\docolon{\ifx=\tmptoken\mathrel{\mathop{\mathchar`\:}}\else\colon\fi}
   \mathcode`\:="8000 %
That lets you do $f: A \to B$ and $f(x) := x^2$
For the second, one can use ≔ COLON EQUALS U+2254. But it is a good point, though.
there is actually a more modern trick:
\starttext
\startluacode
characters.mathpairs[0x3A] = { [0x3D] = 0x2254 }
characters.mathpairs[0x3E] = { [0x3D] = 0x2265 }
characters.mathpairs[0x3C] = { [0x3D] = 0x2264 }
characters.mathpairs[0x3D] = { [0x3A] = 0x2255 }
\stopluacode
\startTEXpage
$a := b <= =< c =: d >= e$
\stopTEXpage
\stoptext
I have experimented with a theorem proof assistant that admitted parallel ASCII and Unicode symbol names, but it turns out to be complicated. Think of C/C++ trigraphs, a chore to implement, only to be removed in the latest standards.

So I think one should only focus on UTF-8, and add TeX ASCII “\” commands as a complement.

One problem with this approach is the lack of Unicode input methods. But that may coming.

For example, instead having “:=“ in the input file and let Lua translate it, one can merely type it and let the text editor translate it ≔ COLON EQUALS U+2254.

It will save a lot of programming time, at least on the ConTEXt project. :-)