Open boxed opened 4 months ago
I started a discussion on the elm #language-design channel about this. It seems several other languages specialcase n / 0 == 0
. Would that be an option? modBy
would then follow the same behaviour.
I was also made aware that Roc
has Checked
versions of such functions. So divChecked
or modByChecked
, which would return a Maybe
. Would that work?
Are there math-functions, other than div
and modBy
, that we should look at as well?
I find it very annoying that I get crashes for divide by zero in python but I also think that just returning zero would cause even more subtle bugs that would be difficult to track down.
I would for example also like to be able to set it so that any production of NaN in python would raise instead. Much nicer than a garbage value that pollutes the execution flow dowstream some arbitrary amount until it is (hopefully!) caught.
Same here with divide by zero and mod. Yea it's annoying but the right thing and the easy thing should be aligned. That's why I would be against "checked" versions: it makes it opt in to do the right thing. You could call that broken by default too.
I would like to propose the following…
intDivBy : Int -> Int -> Maybe Int
modBy : Int -> Int -> Maybe Int
remainderBy : Int -> Int -> Maybe Int
unsafeIntDivBy : Int -> Int -> Int
unsafeModBy : Int -> Int -> Int
unsafeRemainderBy : Int -> Int -> Int
…with the unsafe
variants available for use in performance-sensitive code. This correctly promotes the safe behavior as the default, and highlights the unsafe nature of the high-performance options.
The unsafe
variants would either crash upon division by zero (my preference), or return an undocumented integer result for performance reasons. Either approach (program crash, data corruption) seems reasonable, since the programmer is opting into the unsafe behavior.
It seems several other languages specialcase n / 0 == 0. Would that be an option?
Please, no. I was bitten by an unexpected n // 0 == 0
in an Elm project. I would prefer to have Gren crash on any integer divide-by-zero operation (or even have the //
operator removed from the language), rather than getting unexpected zeroes silently corrupting my results. 🙂
modBy 0 x
crashes with aDebug.crash
(https://github.com/gren-lang/core/blob/098cca86e948f018cea9ca3b10a256b8c89917ba/src/Gren/Kernel/Math.js#L14).I suggest that there be two functions:
which returns
Nothing
on a zero input, and:which does returns a default value on zero.
The reason for the second method is that there is some overhead from the
Maybe
handling which would be a problem in performance sensitive code, as @robinheghan pointed out on zulip. The docs should point out the performance characteristics.I think this is a fairly easy change, but I am a bit scared of touching kernel code of course :P