KOS_OP_MATCH_NEXT

• Style: EXTRA (LABEL, RAW): label, cursor depth.

• Stack: [...] -> [..., e]; jump to a0 with nothing pushed on a miss.

• Semantics: Pull the next element from the cursor at depth a1 and advance the cursor. From a pair spine e is a Datum over the cell’s car, read through Datum, carrying the cell’s position; from a tuple, list or other sequence it is the item; from a single-value cursor, the value. A miss at the cursor’s end, or when the spine cell at the cursor is no longer a pair.

• Compiler form: Emitted by the match compiler for each pattern that consumes one element, ahead of its test. Right after a MATCH_SCOPE on the same cursor, the pair is fused into MATCH_SCOPE_NEXT.