truthful 0.1.1

A logical expression parser, optimizer and evaluator.
Documentation 
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not = @{ "!" | ^"not" }
unary = _{ not }

and = @{ "^" | ^"and" }
or = @{ "v" | ^"or" }
xor = @{ "+" | ^"xor" }
operand = _{ and | or | xor }

cond = @{ "->" | ^"cond" }
bicond = @{ "<->" | ^"bicond" }
equals = @{ "=" | ^"equals" }
linker = _{ cond | bicond | equals }

infix = _{ operand | linker }

ws = _{ " " | "\t" | "\n" }

alpha = _{ 'a'..'z' | 'A'..'Z' }
num = _{ '0'..'9' }

singlequotes = _{ "'" }

identifier = {
    !(unary | operand | linker) ~ alpha ~ ( alpha | num | "_" | "-" )* |
    ( "\"" ~ (!"\"" ~ ANY)* ~ "\"" ) |
    ( "'" ~ (!"'" ~ ANY)* ~ "'" )
}

term = { unary* ~ ws* ~ (identifier | "(" ~ ws* ~ expr ~ ws* ~ ")") }
expr = { term ~ (ws* ~ infix ~ ws* ~ term)* }

statement = { SOI ~ ws* ~ expr ~ ws* ~ EOI }