Token
=====

num [0-9]+
var [a-z]
sym [+-*=,:()]
keyword { PRINT, INPUT, LET, FOR, TO, NEXT, END }
special { REM, EOL, EOF }

Statement
=========

print PRINT expr [',' expr]*
input INPUT var
let LET var '=' expr
for FOR var '=' expr TO expr
next NEXT [var]

Expr
====

expr term ['+'|'-' term]*
term factor ['*' factor]*
factor num
factor var
factor '(' expr ')'

Program
=======

line stmt [':' stmt]* EOL
line EOL
program line* EOF

Not Supported
=============

IF...THEN...ELSE
WHILE...WEND
GOSUB...RETURN
GOTO
DIM/DATA/READ
Float
String
Functions
Commands (NEW/RUN/LIST)
Device (File / Screen / Sound...)
Machine Language