dicetower

• rip-off of the Nearley calculator grammar with dice rolling added in
• a hubot bot that lets you talk to the Nearley grammar

const dicetower = require('dicetower');

dicetower.report('2d6 + 2dF + 2')
// -> *13* (12 (rolled 2d6: 6+6) + -1 (rolled 2dfudge: 1+-2) + 2)

// the number of dice or sides of the dice can be computed via dice roll
dicetower.report('(1d20)d20')
// -> *86* (86 (rolled 11d20: 6+1+3+5+9+5+17+9+11+1+19))

// you can roll custom arbirary dice
dicetower.report('2d4 * 1d[2 3 5 7 9 14]')
// -> *12* (6 (rolled 2d4: 4+2) * 2 (rolled 1d[14 2 3 5 7 9]: 2))

// you can get expected value instead of actually rolling dice
dicetower.report('2d4 * 1d[2 3 5 7 9 14]', true);
// *33.333333333333336*
// (3 (expected 5: 2*2.5) * 7 (expected 6.666666666666667: 1*6.666666666666667))

ok so what's this grammar thing?

I dunno. It's cool. It parses your string and does the calculation. You can read it here. This is a Nearley grammar.

Here's a full list of supported expressions

• parens (3 + 1d4) * 2
• exponents 4^8
• multiplication 4 * 4 and division 4 / 1d2
• addition 1 + 1 and subtraction 2 - 2d4
• a range of mathematical functions and constants sqrt(sin(5)) * pi
• unary negative numbers -1 + 5
• floats and stuff 0.25 * .55
• dice
  • regular dice 2d8
  • fudge dice 4dF
  • dice with arbitrary custom faces 2d[2 4 6 8 10]
  • any value in a dice expression can be an expression (1d6)d[1 2 3 4 2d4 2d8]

how do i hubot

I think this is how:

0. you npm install --save dicetower in your hubot dir
1. you add 'dicetower/lib/hubot_plugin' to your external-scripts.json file