Implement an evaluator for a very simple subset of Forth
Forth is a stack-based programming language. Implement a very basic evaluator for a small subset of Forth.
Your evaluator has to support the following words:
+,-,*,/(integer arithmetic)DUP,DROP,SWAP,OVER(stack manipulation)
Your evaluator also has to support defining new words using the
customary syntax: : word-name definition ;.
To keep things simple the only data type you need to support is signed integers of at least 16 bits size.
You should use the following rules for the syntax: a number is a sequence of one or more (unicode) digits, a word is a sequence of one or more letters, digits, symbols or punctuation that is not a number. (Forth probably uses slightly different rules, but this is close enough.)
Words are case-insensitive.