- bi-iso CONSTRUCT DECONSTRUCT BPprocedure
The bidirectional counterpart of bind. CONSTRUCT turns the flat list of sub-values matched by BP into a single domain value, or returns #f to reject it. DECONSTRUCT does the reverse: it turns a domain value into the flat list BP's printer expects, or returns #f if the value does not belong to this rule. Printing fails if BP's printer does not fully consume what DECONSTRUCT produced, so a rule that is missing or has extra parts fails loudly rather than silently dropping data.