Question

How could user-defined function symbol such as f in

• f[x_] = 2 x

or variable symbols such as lotto in

• lotto = Table[2, {10}];

be colored automatically ?

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In Syntax coloring on M8 no option is offered for this.

Only Local Variables or Global symbols that have no values assigned.

Answer 1

This is not exactly what you asked for, but it may be useful to you.

You can highlight symbols by context, using this method:

SetOptions[$FrontEndSession, 
  AutoStyleOptions -> {"SymbolContextStyles" -> {"highlight`" -> Green}}
]

AppendTo[$ContextPath, "highlight`"];

Now, when you create a symbol in the context highlight` it will automatically be colored green:

highlight`lotto ;

and since highlight` was appended to $ContextPath, after that the symbol can be used plainly:

lotto

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Highlighting all symbols (variables)

If you want all the symbols you create to automatically be highlighted, then set:

$Context = "highlight`"

After that, all new symbols you create will belong to the context highlight` and will receive the color.

New means ones that have not been previously used in the session, or have been Removed.

It occurs to me that a better way to accomplish this, that avoids a possible “shadowing” problem, may be to set highlighting for the Global` context itself. I have not considered the ramifications of this, but it can be done with this alone:

SetOptions[$FrontEndSession, 
  AutoStyleOptions -> {"SymbolContextStyles" -> {"Global`" -> Green}}
]

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Tips on usage

• The context highlight` is completely arbitrary, and you can have multiple contexts highlighted with different colors.

• You can color the contexts of packages such as Units` to distinguish which symbols belong to that package.