ebnf.txt

program ::= {line ";"} line.

line ::= formula | "fun" variable "(" variable ":" typ ")" ":" typ "=>" formula | "if" formula "then" line "else" line "fi" | "let" variable "=" formula "in" line "end".

formula ::= "fn" "(" variable ":" typ ")" ":" typ "=>" formula
	  | formula "EQUALS" formula | formula "GREATERTHAN" formula | formula "LESSTHAN" formula
	  | formula "IMPLIES" formula | formula "AND" formula | formula "OR" formula | formula "XOR" formula
	  | "NEGATE" formula | formula "PLUS" formula | formula "MINUS" formula | formula "TIMES" formula
	  | "NOT" formula | "(" formula ")" | constant | number | variable.

type ::= "int" | "boolean" | type "->" typ | "(" typ ")"

constant ::= "TRUE" | "FALSE".
number ::= Integer {ZeroInteger}.
variable ::= Letter {Letter}.

Letter := “A” | “B” | “C” | “D” | “E” | “F” | “G” | “H” | “I” | “J” | “K” | “L” | “M” | “N” | “O” | “P” | “Q” | “R” | “S” | “T” | “U” | “V ” | “W” | “X” | “Y ” | “Z”
	| “a” | “b” | “c” | “d” | “e” | “f” | “g” | “h” | “i” | “j” | “k” | “l” | “m” | “n” | “o” | “p” | “q” | “r” | “s” | “t” | “u” | “v” | “w” | “x” | “y” | “z”
Integer := "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
ZeroInteger := Integer | "0"