import -- r7rs Definition

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Kind

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syntax;

Implemented by

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• import (from vonuvoli);

Syntax signature

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Syntax keywords:

• import: value of type eval-environment-import;

Syntax variants:

• (_ import |...|)

Exports

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• scheme:base -- (scheme base);

Exports recursive

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• scheme -- (scheme);

Description

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(import <import-set> ...)

An import declaration provides a way to import identifiers exported by a library. Each <import-set> names a set of bindings from a library and possibly specifies local names for the imported bindings. It takes one of the following forms:

• <library-name>
• (only <import-set> <identifier> ...)
• (except <import-set> <identifier> ...)
• (prefix <import-set> <identifier>)
• (rename <import-set> (<identifier_1> <identifier_2>) ...)

In the first form, all of the identifiers in the named library's export clauses are imported with the same names (or the exported names if exported with rename). The additional <import-set> forms modify this set as follows:

• only produces a subset of the given <import-set> including only the listed identifiers (after any renaming). It is an error if any of the listed identifiers are not found in the original set.

• except produces a subset of the given <import-set>, excluding the listed identifiers (after any renaming). It is an error if any of the listed identifiers are not found in the original set.

• rename modifies the given <import-set>, replacing each instance of <identifier_1> with <identifier_2>. It is an error if any of the listed <identifier_1>s are not found in the original set.

• prefix automatically renames all identifiers in the given <import-set>, prefixing each with the specified <identifier>.

In a program or library declaration, it is an error to import the same identifier more than once with different bindings, or to redefine or mutate an imported binding with a definition or with set!, or to refer to an identifier before it is imported. However, a REPL should permit these actions.

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The text herein was sourced and adapted as described in the "R7RS attribution of various text snippets" appendix.

Referenced-types

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• eval-environment-import;