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Creating Modules

syntax: module <body>

procedure: make-module expression

procedure: load-module filename

<Body> should be a sequence of one or more definitions and expressions. Module sequentially evaluates the expressions and definitions of <body> in a scheme report environment. Definitions occuring at the top level cause bindings to be created in the binding contour which the call to module creates and returns.

Make-module evaluates expression in a scheme report environment. Definitions occuring at the top level cause bindings to be created in the binding contour which the call to make-module creates and returns.

Filename should be a string naming an existing file containing Scheme source code. The load-module procedure reads expressions and definitions from the file and evaluates them sequentially in a scheme report environment. Definitions occuring at the top level cause bindings to be created in the binding contour which the call to load-module creates and returns.

The load-module procedure does not effect the values returned by current-input-port and current-output-port.

Rationale: For portability, load-module must operate on source files. Its operation on other kinds of files necessarily varies among implementations.

The expressions evaluated in these calls are evaluated in a fresh scheme report environment. The current environment has no effect on the module.
If an (evaluated) expression executes a call to load, any top level bindings made in the loaded code are treated as though they were part of the expression.
If an expression executes a call to import-module, any top level bindings imported by import-module, although visible to the module code, are not automatically exported.
Loading source for a new module into a fresh scheme report environment ensures that every procedure defined in the module is integrable unless source analysis reveals otherwise. Source not found during lexical analysis will not effect the module's operation. Hence, a compiler can close the world on every module.
Each module must import all the modules it needs.
Since identifiers bound to modules will not be visible while evaluating module source, the mechanism for translating module names to filenames should be part of the scheme report environment (although not specified in the report).
Module, make-module, and load-module can each be defined in terms of Module, make-module, or load-module.

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