I think a recent update (March 3rd, version 2.5.3) to SBCL added this sorta breakpoint debugging functionality. Hopefully we'll see it integrated with SLIME soon.
> enhancement: breakpoint debugger commands have been added. Included is a stepper based on breakpoints requiring no extra instrumentation. However, it still has less functionality than the existing single stepper. See the new debugger manual section titled "Breakpoint Commands" for more information on the new commands.
Oh wait, Hackernews seems to have removed one of the astericks symbols. It should be Python's exponentiation operator (2 astericks symbols), ya. (edit: fixed now).
That's a question of interface design. You can also create ugly, ambiguous interfaces with functions (10 arguments, it mutates some of them, etc), or any other language feature. If a library designer uses operator overloading well, then it should be obvious what "a+b" is doing if you know the types involved.
On one hand it's a question of philosophy -- do you provide the user with tools to better express themselves, if they might possibly shoot themselves in the foot and create a crappy interface?
On the other hand, it could be an engineering issue. Maybe it's not worth the technical challenge or the increase in complexity for the language designers. I'd be more sympathetic to this reason. Then again, Python and C++ manage it.
Here's a not-so-mathy application that I had recently. I was implementing a units system in Python. Operator overloading allowed me to define joules like so: `J = KG * M**-1 * S**-2`. Then I could define grays (a radiation-related unit) like `Gy = J/KG`. Repeat for hundreds of units. If I had to do it in Java, I'd be frustrated by the verbosity and it would be easier to make mistakes.
My point -- Guy's point, actually -- is that if you don't give people the ability to grow a language, then their expressive power will be limited. And you can't anticipate ahead of time all the ways they'll want to express themselves.
Admittedly, my application is kinda mathy under the hood, because the units exist in a vector space. I guess that's to be expected when the operators come from maths.
My favourite illustration of this is in The Wire. The city wants to crack down on crime and increases the target number of arrests. The police chief sends out the word and police officers begin making a bunch of spurious arrests. Do you blame the politicians for picking crappy metrics and for their poor understanding of human nature? Or do you blame the individuals who choose to exploit the metric out of self-interest? Plenty of blame to go around.
The previous user said that you can do "literally anything" in VSCode that you can do in Emacs, I think these examples were chosen to prove that statement wrong. It doesn't mean that Emacs is better for everyone.
I actually started working on a CLI calculator a few days ago that sounds exactly like what you're looking for: https://github.com/Kevinpgalligan/ka
So far it just has variables and basic arithmetic. Other features on my roadmap: rational numbers, a type hierarchy, units, and lazy/smart combinatorics.
What do you imagine the timezone DB would look like? I'd love to hear your ideas!
> enhancement: breakpoint debugger commands have been added. Included is a stepper based on breakpoints requiring no extra instrumentation. However, it still has less functionality than the existing single stepper. See the new debugger manual section titled "Breakpoint Commands" for more information on the new commands.