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Thanks for the honest reply. Nim interests me but this nil business seems questionable to me. Just found this comment from the language creator, https://gith

Thanks for the honest reply. Nim interests me but this nil business seems questionable to me. Just found this comment from the language creator, https://github.com/nim-lang/Nim/issues/6638#issuecomment-487633727 https://github.com/nim-lang/Nim/issues/6638#issuecomment-487... "We need the nil state to disarm pointers but that only means these can be nil and so would require a nil check before deref. Doesn't seem to be too hard nor too cumbersome." Seems a bit dismissive to me

gmfawcett 6y ago
I agree that it's a sharp edge in the language. Or at least it seems to be -- I've written a little bit of Nim, and never encountered a case where I was actually bitten by 'nil'. The language does have a 'non nil' annotation that can be used when defining structs (and maybe in other parts of the language, I don't recall), so there must have been some thinking about the dangers of nil pointers. I would still recommend playing with the language for a while. It's quite practical, and the performance is very good. I've used it to write some utilities where I might otherwise use Python, but either needed more speed or needed to use it in a restricted environment where the Python interpreter wasn't available. The experience was mostly positive, and I would use it again.
- Isomorpheus 6y ago
  Thanks, I intend to give it a fair try
- elcritch 6y ago
  P.S., you can annotate procedure to help ensure you can’t raise certain conditions in code. Imho it’s nice for writing sections of “safe” code.
mratsim 6y ago
`non-nil` was deemed too breaking to introduce for 1.0 or even as a default because if you tagged your input as `T not nil` the compiler was not powerful enough to prove that T was indeed not nil except in the most obvious cases. The new battleplan is to integrate the Z3 theorem prover into Nim as DrNim: - https://nim-lang.org/docs/drnim.html https://nim-lang.org/docs/drnim.html The first use-case will be proving array bounds at compile-time and elide them. Future use-cases include not nil tracking.
- Isomorpheus 6y ago
  This sounds pretty cool, but, two thoughts 1) Echoing the other comments in this thread about uneasiness with feature creep 2) Wouldn't have been a breaking change if the language didn't have nil from the beginning
  - mratsim 6y ago
    1: DrNim is basically additional annotations that are ignored, and you can choose to opt-in via a flag. It's something you similar to MyPy for python and type annotations. The danger is if it becomes non-optional. That said contrary too many languages, the core language doesn't need: - threading - async which are huge parts to maintain, but thanks to metaprogramming you can implement them as libraries with very nice syntax as well. It also allows compiler devs to focus on what they know well, compilers and leave those 2 highly specialized areas to people who are experts (or become experts) in those. 2: There are 2 dimensions there: nil is used for C FFI, for higher-level primitives you can use Option. And C FFI was needed to bootstrap Nim with a useful set of functionality and has an escape hatch so that people could start building early on and not wait for the language. So both from a functionality and a time-to-market point of view it was necessary.
planetis 6y ago
That's an old comment by the way. At that time the newruntime idea was tested (and now replaced by --gc:arc). One needs to be more careful when using others words, especially taken out of context.

gmfawcett 6y ago

I agree that it's a sharp edge in the language. Or at least it seems to be -- I've written a little bit of Nim, and never encountered a case where I was actually bitten by 'nil'. The language does have a 'non nil' annotation that can be used when defining structs (and maybe in other parts of the language, I don't recall), so there must have been some thinking about the dangers of nil pointers. I would still recommend playing with the language for a while. It's quite practical, and the performance is very good. I've used it to write some utilities where I might otherwise use Python, but either needed more speed or needed to use it in a restricted environment where the Python interpreter wasn't available. The experience was mostly positive, and I would use it again.

Isomorpheus 6y ago
Thanks, I intend to give it a fair try
elcritch 6y ago
P.S., you can annotate procedure to help ensure you can’t raise certain conditions in code. Imho it’s nice for writing sections of “safe” code.

mratsim 6y ago

`non-nil` was deemed too breaking to introduce for 1.0 or even as a default because if you tagged your input as `T not nil` the compiler was not powerful enough to prove that T was indeed not nil except in the most obvious cases. The new battleplan is to integrate the Z3 theorem prover into Nim as DrNim: - https://nim-lang.org/docs/drnim.html https://nim-lang.org/docs/drnim.html The first use-case will be proving array bounds at compile-time and elide them. Future use-cases include not nil tracking.

Isomorpheus 6y ago
This sounds pretty cool, but, two thoughts 1) Echoing the other comments in this thread about uneasiness with feature creep 2) Wouldn't have been a breaking change if the language didn't have nil from the beginning
- mratsim 6y ago
  1: DrNim is basically additional annotations that are ignored, and you can choose to opt-in via a flag. It's something you similar to MyPy for python and type annotations. The danger is if it becomes non-optional. That said contrary too many languages, the core language doesn't need: - threading - async which are huge parts to maintain, but thanks to metaprogramming you can implement them as libraries with very nice syntax as well. It also allows compiler devs to focus on what they know well, compilers and leave those 2 highly specialized areas to people who are experts (or become experts) in those. 2: There are 2 dimensions there: nil is used for C FFI, for higher-level primitives you can use Option. And C FFI was needed to bootstrap Nim with a useful set of functionality and has an escape hatch so that people could start building early on and not wait for the language. So both from a functionality and a time-to-market point of view it was necessary.

planetis 6y ago

That's an old comment by the way. At that time the newruntime idea was tested (and now replaced by --gc:arc). One needs to be more careful when using others words, especially taken out of context.