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
3 2 swap - // -1

DROP

Mnemonics: a -> _

Drops element from stack

Example:

2 2 100 drop + // 4, and empty stack

COPY

Mnemonics: a -> a a

Copies element from stack

Example:

2 copy // 2 2 on stack

Tips and Tricks

• swap is useful when initializing local variables by function arguments values. For example: gofra func int str2int[ *char[], int ] do var len int; &len swap !< var ptr *char[]; &ptr swap !< ... end In this example, the len variable is initialized by the int value from the arguments and the ptr variable is initialized by the *char[] value from the arguments.

• copy is useful when increasing or decreasing some value. For example: ``` var number int = 0;

  &number copy ?> 10 + !< // number = number + 10 ```