Function patch_seq_pick_op 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn patch_seq_pick_op(stack: Stack) -> Stack

Pick operation exposed to compiler

Copies a value from depth n to the top of the stack.

Stack effect: ( ..stack n – ..stack value ) where n is how deep to look (0 = top, 1 = second, etc.)

Examples

10 20 30 0 pick   # Stack: 10 20 30 30  (pick(0) = dup)
10 20 30 1 pick   # Stack: 10 20 30 20  (pick(1) = over)
10 20 30 2 pick   # Stack: 10 20 30 10  (pick(2) = third)

Common Equivalences

• pick(0) is equivalent to dup - copy top value
• pick(1) is equivalent to over - copy second value
• pick(2) copies third value (sometimes called “third”)
• pick(n) copies value at depth n

Use Cases

Useful for building stack utilities like:

• third: 2 pick - access third item
• 3dup: 2 pick 2 pick 2 pick - duplicate top three items
• Complex stack manipulations without excessive rot/swap

Safety

Stack must have at least one value (the Int n), and at least n+1 values total