12.9 Expanding Top-Level Forms

Before top-level-form is expanded, its lexical context is enriched with namespace-syntax-introduce, just as for eval. Use syntax->datum to convert the returned syntax object into a printable datum.

Here’s an example of using expand on a module:

(parameterize ([current-namespace (make-base-namespace)])

(expand

(datum->syntax

#f

'(module foo scheme

(define a 3)

(+ a 4)))))

Here’s an example of using expand on a non-top-level form:

(define-namespace-anchor anchor)

(parameterize ([current-namespace

(namespace-anchor->namespace anchor)])

(expand

(datum->syntax

#f

'(delay (+ 1 2)))))

Before top-level-form is expanded, its lexical context is enriched with namespace-syntax-introduce, as for eval.

Before stx-or-sexpr is expanded, its lexical context is enriched with namespace-syntax-introduce, as for eval.

12.9.1 Information on Expanded Modules

Information for an expanded module declaration is stored in a set of syntax properties (see Syntax Object Properties) attached to the syntax object:

• 'module-direct-requires — a list of module path indexes (or symbols) representing the modules explicitly imported into the module.

• 'module-direct-for-syntax-requires — a list of module path indexes (or symbols) representing the modules explicitly for-syntax imported into the module.

• 'module-direct-for-template-requires — a list of module path indexes (or symbols) representing the modules explicitly for-template imported into the module.

• 'module-variable-provides — a list of provided items, where each item is one of the following:

  • symbol — represents a locally defined variable that is provided with its defined name.

  • (cons provided-sym defined-sym) — represents a locally defined variable that is provided with renaming; the first symbol is the exported name, and the second symbol is the defined name.

  • (list* module-path-index provided-sym defined-sym) — represents a re-exported and possibly re-named variable from the specified module; module-path-index is either a module path index or symbol (see Compiled Modules and References), indicating the source module for the binding. The provided-sym is the external name for the re-export, and defined-sym is the originally defined name in the module specified by module-path-index.

• 'module-syntax-provides — like 'module-variable-provides, but for syntax exports instead of variable exports.

• 'module-indirect-provides — a list of symbols for variables that are defined in the module but not exported; they may be exported indirectly through macro expansions. Definitions of macro-generated identifiers create uninterned symbols in this list.