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Nimony (Nim 3.0) Design Principles

Nimony (Nim 3.0) Design Principles

7 comments

·December 2, 2025
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kbd

The biggest thing I still don’t like about Nim is its imports:

    import std/errorcodes

    proc p(x: int) {.raises.} =
      if x < 0:
        raise ErrorCode.RangeError
      use x
I can’t stand that there’s no direct connection between the thing you import and the names that wind up in your namespace.

PMunch

There is a direct connection, you just don't have to bother with typing it. Same as type inference, the types are still there, you just don't have to specify them. If you have a collision in name and declaration then the compiler requires you to specify which version you wanted. And with language inspection tools (like LSP or other editor integration) you can easily figure out where something comes from if you need to. Most of the time though I find it fairly obvious when programming in Nim where something comes from, in your example it's trivial to see that the error code comes from the errorcodes module.

xigoi

It needs to be this way so that UFCS works properly. Imagine if instead of "a,b".split(','), you had to write "a,b".(strutils.split)(',').

polotics

ok I do not understand.

What is preventing this import std/errorcodes

from allowing me to use: raise errorcodes.RangeError instead of what Nim has?

or even why not even "import std/ErrorCodes" and having the plural in ErrorCodes.RangeError I wouldn't mind

mwkaufma

Big "college freshman" energy in this take:

  I personally prefer to make the error state part of the objects: Streams can be in an error state, floats can be NaN and integers should be low(int) if they are invalid (low(int) is a pointless value anyway as it has no positive equivalent).
It's fine to pick sentinel values for errors in context, but describing 0x80000000 as "pointless" in general with such a weak justification doesn't inspire confidence.

ratmice

Without the low int the even/odd theorem falls apart for wrap around I've definitely seen algorithms that rely upon that.

I would agree, whether error values are in or out of band is pretty context dependent such as whether you answered a homework question wrong, or your dog ate it. One is not a condition that can be graded.

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