DieRoller

An interpreter for a simple language so you can roll dice more easily.

How to use:

An expression may be:

• an integer
• a unary operator followed by an expression
• an expression followed by a binary operator followed by a binary operator
• an expression contained within parentheses '(' and ')'

The unary operators are:

• + - unary addition (does nothing)
• - - additive inverse (works as expected)
• d - rolls a die of specified size

The binary operators are:

• + - addition (works as expected)
• - - subtraction (works as expected)
• d - roll dice

How the unary and binary d works.

The d is called the die roll operator or die operator for short. There is a unary and binary version of the die operator, however the unary may be converted into the binary version

Let A and B be valid expressions. Then the expression AdB would work as

1. Evaluate A, let us call the result a.
2. Evaluate B, let us call the result b.
3. Roll a b sided die a times and return the sum.

• The d operator is only defined if a >= 0 and b > 0

The expression dA would be equivlent to 1dA. So if A evaluates to the result a then we roll one a sided die and return the result.

Definition of die:

When we say roll a die we must specific. A die with n sides has numbers {1, 2, ..., n}, and each value is equally likely. More specifically rolling a die with n sides returns a positive integer less than or equal to n with a uniform probability distribution.

Order of operations:

Precedence level	Name	Type of operator	Associativity	Operators
0	Unary Arithmatic	Unary Prefix	N/a	+, -, d
1	Die Operation	Binary	Left	d
2	Arithmatic	Binary	Left	+, -