6.5 Exports: provide

By default, all of a module’s definitions are private to the module. The provide form specifies definitions to be made available where the module is required.

(provide provide-spec ...)

A provide form can only appear at module level (i.e., in the immediate body of a module). Specifying multiple provide-specs in a single provide is exactly the same as using multiple provides each with a single provide-spec.

Each identifier can be exported at most once from a module across all provides within the module. More precisely, the external name for each export must be distinct; the same internal binding can be exported multiple times with different external names.

The allowed shape of a provide-spec is defined recursively:

identifier

In its simplest form, a provide-spec indicates a binding within its module to be exported. The binding can be from either a local definition, or from an import.

(rename-out [orig-id export-id] ...)

A rename-out form is similar to just specifying an identifier, but the exported binding orig-id is given a different name, export-id, to importing modules.

(struct-out struct-id)

A struct-out form exports the bindings created by (define-struct struct-id ....).

See Programmer-Defined Datatypes for information on define-struct.

(all-defined-out)

The all-defined-out shorthand exports all bindings that are defined within the exporting module (as opposed to imported).

Use of the all-defined-out shorthand is generally discouraged, because it makes less clear the actual exports for a module, and because PLT Scheme programmers get into the habit of thinking that definitions can be added freely to a module without affecting its public interface (which is not the case when all-defined-out is used).

(all-from-out module-path)

The all-from-out shorthand exports all bindings in the module that were imported using a require-spec that is based on module-path.

Although different module-paths could refer to the same file-based module, re-exporting with all-from-out is based specifically on the module-path reference, and not the module that is actually referenced.

(except-out provide-spec id ...)

Like provide-spec, but omitting the export of each id, where id is the external name of the binding to omit.

(prefix-out prefix-id provide-spec)

Like provide-spec, but adding prefix-id to the beginning of the external name for each exported binding.