tuck
| Input Stack: |
⇨ |
Output Stack:| top: Any | | second: Any | | top: Any |
|
Copy the top item to the third position on the stack. This is equivalent to the sequence :swap,:over
and is useful when you need the top item to be accessible after a binary operation.
Parameters
- top: The item currently at the top of the stack that will be copied to the third position
- second: The item in the second position (remains unchanged)
Examples
Basic tuck operation:
a,b,:tuck
| Pos | Input | Output |
| 0 |
b |
b |
| 1 |
a |
a |
| 2 |
|
b |
Equivalent sequence using swap and over:
a,b,:swap,
:over
- :over - Copy the second item to the top
- :swap - Exchange the top two items
- :dup - Duplicate the top item