std/units

[timotheecour]

proposal

std/units

example

runnableExamples:
  type
    Length = "m".makeUnit # can be also defined from other powers of other units
    Time = "s".makeUnit
    Mass = "kg".makeUnit

  var a = Time(1.2)
  var b = Length(3.2)
  var c = Mass(5.4)

  assert $a.float == "1.2"
  assert $a == "1.2's"
  assert $(a*a*a) == "1.728's³"
  assert $(a*a*a*b*b) == "17.69472's³*m²"
  assert $b == "3.2'm"
  assert $(a*b) == "3.84's*m"
  assert $(a/b*c*c) == "10.935's*1/m*kg²"
  assert $(Time(1.2)/Length(3.2)*Mass(5.4)*Mass(5.4)) == "10.935's*1/m*kg²"

implementation

I implemented this in a private branch.

note

it's a completely different approach from https://github.com/def-/nim-units/blob/master/units.nim, which is a hacky/not general/more complex solution that hardcodes fixed units (and fixed powers of such units, eg you can't get s^3 unless you hardcode it)