Symmetry on Experiments with Nimrod

Comment on Experiments with Nimrod parent

I'm looking forward to ROS2 using DDS, which will give zero copy IPC for nodes on the same computer. [1]

I wouldn't say that Rust is bad at talking about compile time versus runtime, just that Nimrod is better. This throws a compile error in Rust, for instance:

      static FOOBAR: int = if 2i > 1i { 10 } else { 20 };

But this doesn't in Nimrod:

  when 2 > 1:
    const FOOBAR = 10
  else:
    const FOOBAR = 20

And that's all because Nimrod added this 'when' keyword distinct from 'if' for stuff that gets computed at compile time. I wouldn't need something like that in a non-embedded context (I guess it's used for specializing to a given operating system by the creator?) but I'll happily use it.

[1]http://design.ros2.org/

dom96 12y

Keep in mind that Nimrod will also try to evaluate normal code at compile-time, so the following will work fine:

    const FOOBAR = if 2 > 1: 10 else: 20

Symmetry 12y

What I'd actually be doing is more like:

  when ROBOT_VER == 32:
    type TSonarAddresses = array[0..3, int]
    const sonarAddresses: TSonarAddresses = [1,2,3,4]
    ...
  elif ROBOT_VER == 33:
    ...

and stuff like that.

dom96 12y

I see. Good, that is precisely what 'when' should be used for :)

rurban 12y

This is called "constant folding", and every better compiler should do that.

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