3.3 Variable References and #%top
id |
Refers to a module-level or local binding, when id is not bound as a transformer (see Expanding Top-Level Forms). At run-time, the reference evaluates to the value in the location associated with the binding.
When the expander encounters an id that is not bound by a module-level or local binding, it converts the expression to (#%top . id) giving #%top the lexical context of the id; typically, that context refers to #%top. See also Expansion Steps.
Examples: |
> (define x 10) |
> x |
10 |
> (let ([x 5]) x) |
5 |
> ((lambda (x) x) 2) |
2 |
(#%top . id) |
Refers to a top-level definition that could bind id, even if id has a local binding in its context. Such references are disallowed anywhere within a module form. See also Expansion Steps for information on how the expander introduces #%top identifiers.
Examples: |
> (define x 12) |
12 |