Stack management operators

For managing an stack you must have some less-or-more complex commands for example like swap or rot, language supports some of them

SWAP

Mnemonics: a b -> b a

Swaps two arguments from stack, for example for reaching second argument

Example

3 2      - // 1
2 3 swap - // -1

DROP

Mnemonics: a -> _

Drops element from stack

Example:

2 2 2 drop + // 4, and empty stack

COPY

Mnemonics: a -> a a

Copies element from stack

Example:

2 copy // 2 2 on stack