This a code source for a mini interpreter that work with two instructions (let/print) ,with a nice interface made using javaFx and CSS.
this is the BNF for the interpreter: ::="print" |"let" "=" ::=[ "-" ] [ [ "+" | "-" ] ]... ::= [ [ "*" | "/" ] ]... ::= [ "^" ]... ::= | | "(" ")"| "(" ")" ::= { | } ::= {}