Need to evaluate dice notation in Swift? This package is for you.

let roll = Roll("1d20")!.roll()
roll.result
// $R0: Int = 18

let roll = Roll("3d8+1d6")!.roll()
roll.result
// $R0: Int = 19
roll.expression
// $R1: String = "1+6+7+5"

// Percentage die shorthand is also supported.
let roll = Roll("d%")

D(20).average
// $R0: Double = 10.5

The rest of the API is pretty self-explanatory. Dice and Rolls have attributes for accessing the max, half and average values of their rolls. Use the roll() function to actually throw the dice on both of these types and get some random values.

This package also includes a small CLI to roll the dice directly in your terminal.

$ d20 2d6+4
# 14 (6+4)+4

$ alias dagger='d20 1d4+2'
$ dagger
# 6 (4)+2
# CRIT!

# Invoke it without an argument to enter REPL mode.
$ d20
> d4
3 (3)
> 2d4
6 (2+4)

Installing it is easy. Just run the following after cloning the repo.

$ swift build -c release
$ cp .build/release/d20 /usr/local/bin/d20

D20 by Lonnie Tapscott from the Noun Project