I hope the [expr] command gets deprecated
Since https://core.tcl-lang.org/tips/doc/trunk/tip/174.md%|%TIP 174: Math Operators as Commands%|%
I would have hoped that all future improvement would go into Math Commands
But I see several pending tip suggesting improvements to the [expr] command
* https://core.tcl-lang.org/tips/doc/trunk/tip/526.md%|%TIP 526: Make [expr] Only Accept One Argument%|%
* https://core.tcl-lang.org/tips/doc/trunk/tip/408.md%|%TIP 408: Allow Any Command for expr Functions%|%
* https://core.tcl-lang.org/tips/doc/trunk/tip/282.md%|%TIP 282: Enhanced Expression Syntax%|%
I hope that those tips get abandoned or withdrawn
Adding mini languages to Tcl is in my opinion very bad language design and adds complexity
I understand that [expr] is part of Tcl's history and heritage, but I think as Tcl seem moving toward version 9
and hopefully towards a slight revival, I think its also time to just declare commitment to Tcl's command syntax
it is in my opinion cleaner and less confusing and promotes homoiconicity better (for my poor understanding of what homoiconicity means)
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'''[KJN] 2023-04-16 17:45:00'''
When learning Tcl it was surprising to find that the syntax of `[expr]` did not conform to the usual Tcl rules - for example, it is necessary to quote a string literal, but not a string that is the value of a variable.
It might be possible to "improve" `[expr]` syntax - for example, now that we have the string operators "eq" and "ne", is it useful to allow "==" and "!=" to perform string comparisons when their arguments are not numbers? Further "improvements" are possible if spaces are required between the elements of an expression, but at the cost of breaking old code and consistency with other languages.
In any case, we need `[expr]` if we want to do numerical operations with infix notation. I much prefer
======tcl
expr {sin($theta * $pi / 180.)**2}
======
to the Tcl-compliant form
======tcl
** [sin [/ [* $theta $pi] 180.]] 2
======
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'''[stevel] 2023-03-01 08:14:18'''
I don't see `[expr]` ever being deprecated, but do think a discussion of ways to better handle expressions would be helpful. As you have noted, there are already proposals on the table.
At present there is a focus on getting 9.0 out the door but there's no reason why you couldn't revive the discussion with a view to the feature being in Tcl 9.1. A good place to start would be [Math Operators as Commands].
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'''[SYStems] 2023-03-01 12:42:19 PM'''
Tcl is a nice glue language, the ultimate glue language in my opinion.
I think the command line interface is the best option for glue languages
I also like a lot [John Ousterhout] [Ousterhout's Dichotomy].
So Tcl hosting secondary language is not necessarily a horrible idea.
[regexp] can be considered as a mini or secondary language inside Tcl.
But I can't think of math operators as mini language,
so I think either `[expr]` should be deprecate or be repositioned as a gateway (interface) to
a more complete math system (another language/interpreter that does math better)
This way Tcl can delegate Math / Regexp to other interpreters that have better implementations for those features.
[PYK] 2023-03-03: Math operators as individual procedures do not expose the
full power of `[expr]`, which provides parenthesis for grouping and precedence,
and also provides the logical operators, which are lazy in the sense that only
the true branches are evaluated. `[expr]` is one of the standard languages Tcl
provides. It's useful and it is here to stay. `[expr]` could one day provide
and assignment operator and even provide ";" as an expression delimiter. Maybe
it will. In the meantime, there's nothing stopping anyone from implementing
another command that provides access to another math system. That's what Tcl
is for.