(guile.info.gz) General Information about Modules

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(guile.info.gz) The Guile module system

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 31.3.1 General Information about Modules
 ----------------------------------------
 
 A Guile module can be thought of as a collection of named procedures,
 variables and macros.  More precisely, it is a set of "bindings" of
 symbols (names) to Scheme objects.
 
    An environment is a mapping from identifiers (or symbols) to
 locations, i.e., a set of bindings.  There are top-level environments
 and lexical environments.  The environment in which a lambda is
 executed is remembered as part of its definition.
 
    Within a module, all bindings are visible.  Certain bindings can be
 declared "public", in which case they are added to the module's
 so-called "export list"; this set of public bindings is called the
 module's "public interface" ( Creating Guile Modules).
 
    A client module "uses" a providing module's bindings by either
 accessing the providing module's public interface, or by building a
 custom interface (and then accessing that).  In a custom interface, the
 client module can "select" which bindings to access and can also
 algorithmically "rename" bindings.  In contrast, when using the
 providing module's public interface, the entire export list is available
 without renaming ( Using Guile Modules).
 
    To use a module, it must be found and loaded.  All Guile modules
 have a unique "module name", which is a list of one or more symbols.
 Examples are `(ice-9 popen)' or `(srfi srfi-11)'.  When Guile searches
 for the code of a module, it constructs the name of the file to load by
 concatenating the name elements with slashes between the elements and
 appending a number of file name extensions from the list
 `%load-extensions' ( Loading).  The resulting file name is then
 searched in all directories in the variable `%load-path' ( Build
 Config).  For example, the `(ice-9 popen)' module would result in the
 filename `ice-9/popen.scm' and searched in the installation directories
 of Guile and in all other directories in the load path.
 
    Every module has a so-called syntax transformer associated with it.
 This is a procedure which performs all syntax transformation for the
 time the module is read in and evaluated.  When working with modules,
 you can manipulate the current syntax transformer using the
 `use-syntax' syntactic form or the `#:use-syntax' module definition
 option ( Creating Guile Modules).
 
    Please note that there are some problems with the current module
 system you should keep in mind ( Module System Quirks).  We hope
 to address these eventually.
 

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(guile.info.gz) The Guile module system

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