Module order 

Standard order of terms (ISO 8.4.2).

Order: Var < Number < Atom < Compound

• vars among themselves by heap-cell index
• numbers by value; Float < Integer when numerically equal; NaN last
• atoms alphabetically by name
• compounds by arity, then functor name, then args left-to-right

A LST cell IS the compound '.'(Head, Tail) — arity 2, functor “.”. We treat it as such so a LST and a STR with functor “.” / arity 2 compare structurally equal.

Functions

compare_terms

Total standard order over two heap words (after dereferencing).