math.lark

// start: root ("\n" root)? "\n"*
?start: equation
      | expr

// equation: expr "=" expr -> eqn

equation: VAR "=" expr  -> asn
        | expr "=" expr -> eqn




// this could be _expr to make it explicit
// because every use of expr only has one child
// so it is a useless wrapper to preserve
?expr: sum
     | product
     | exponent
     | atom

?sum: sum "+" product  -> add
    | sum "-" product  -> sub
    | product


?product: product "*" exponent  -> mul
        | product "/" exponent  -> div
        | exponent

?exponent: atom "**" atom -> exp
         | atom


?atom: NUMBER            -> num
     | VAR               -> var
     | "(" expr ")"      -> par
     | FUNC "(" expr ")" -> fun
     | "-" atom          -> neg

VAR: LCASE_LETTER


FUNC: "sin"
    | "cos"
    | "tan"
    | "sqrt"
    | "log"
    | "ln"

%import common.NUMBER
%import common.LCASE_LETTER
%import common.WS_INLINE

%ignore WS_INLINE // tabs and spaces