unbound variables造句

• A term is " closed " if there are no unbound variables.
• Examples for formulas are ? ( or ? ( x ) to mark the fact that at most x is an unbound variable in ? ) and ? defined as follows:
• In languages like C + +, accessing an unbound variable does not have well-defined semantics and may result in undefined behavior, similar to referring to a dangling pointer; and declarations or identifiers used outside their scope will generate syntax errors.
• At the minimum tokenization is required, and typically syntactic analysis and basic semantic checks ( unbound variables ) will still be performed  so there is no benefit to the front end  and optimization requires ahead-of-time analysis  so there is no benefit to the middle end.
• In this case any variables in the nested function that are not local to it ( unbound variables in the function definition, that resolve to variables in an enclosing context ) create a closure, as not only the function itself, but also its environment ( of variables ) must be returned, and then potentially called in a different context.