The pseudostack is a virtual structure that uses Arrays to simulate a stack. Unlike a true stack, the pop operation cannot be used to read the first-out value. Therefore, peek must be used prior to pop. Because query requires homogenous data types, pseudostacks are string-only structures.
All three operations are comparatively efficient. Applications of this structure are rare and typically occur in algorithmic formulae.

Operations

Push

{<string>; pstack}

Pop

query(pstack, "offset 1",)

Peek

single(pstack)