As far as I can tell, there's no way to describe dice rolls where parts of the roll depend on another, so you can't for example express something like a standard attack and damage roll in D&D, where you roll an attack roll against some AC, doing no damage if you don't roll above a certain number, doing some damage if you do. Alternatively you do extra damage on a 20.

My motivation for this is, for my D&D character, I want to see how much damage each of my attacks do in various situations. So I want to say "Roll a d20 + some modifier, if it's higher than this AC, roll these dice to do this much damage." I've been doing that experimentally since computation is cheap and I can approximate the actual results well enough, but I feel like it should be possible to do analytically.

Currently there is no operator for subtracting dice:

roll(d100 - d100)
ERROR: MethodError: no method matching -(::Dice, ::Dice)
Closest candidates are:
  -(::ChainRulesCore.AbstractThunk, ::Any) at ~/.julia/packages/ChainRulesCore/uxrij/src/tangent_types/thunks.jl:32
  -(::ChainRulesCore.NoTangent, ::Any) at ~/.julia/packages/ChainRulesCore/uxrij/src/tangent_arithmetic.jl:61
  -(::ChainRulesCore.ZeroTangent, ::Any) at ~/.julia/packages/ChainRulesCore/uxrij/src/tangent_arithmetic.jl:101
  ...
Stacktrace:
 [1] top-level scope
   @ REPL[23]:1

It would be great to add such functionality.

For instance roll"1d5".

• To make sure they run
• To expose examples
• To check their range
• To show what's missing

Something like issubset([roll"..." for _ = 1:N], ra:rb]), for instance should work for the first 3 points above.

For instance

macro r_str(str)
    # Parse the string and call appropriate functions
end

so that it's easier to run with bots, for instance.

Examples of rolls that would be interesting:

r"2#1d20+6" # Rolls 1d20+6 twice
r"2d20kh1" # Rolls 2d20 and keeps highest
r"Adv 1d20+6" # Rolls  1d20+6 twice and keeps highest (same as `kh1`).

cf. @Jualns @Lucas-Akio

Ported from Dices.jl. Issue by @xiaodaigh

I think it's better to not auto export these common short names.

using Dices: d4, d6

if I want to use these dices would be better.

Currently works for roll"3d4". Needs to work for roll"1d6+1d4" as well.