6.18.6 Loading Scheme Code from File

Scheme Procedure: load filename [reader]

Load filename and evaluate its contents in the top-level environment.

reader if provided should be either #f, or a procedure with the signature (lambda (port) …) which reads the next expression from port. If reader is #f or absent, Guile’s built-in read procedure is used (see Scheme Read).

The reader argument takes effect by setting the value of the current-reader fluid (see below) before loading the file, and restoring its previous value when loading is complete. The Scheme code inside filename can itself change the current reader procedure on the fly by setting current-reader fluid.

If the variable %load-hook is defined, it should be bound to a procedure that will be called before any code is loaded. See documentation for %load-hook later in this section.

Scheme Procedure: load-compiled filename

Load the compiled file named filename.

Compiling a source file (see Read/Load/Eval/Compile) and then calling load-compiled on the resulting file is equivalent to calling load on the source file.

Scheme Procedure: primitive-load filename

C Function: scm_primitive_load (filename)

Load the file named filename and evaluate its contents in the top-level environment. filename must either be a full pathname or be a pathname relative to the current directory. If the variable %load-hook is defined, it should be bound to a procedure that will be called before any code is loaded. See the documentation for %load-hook later in this section.

C Function: SCM scm_c_primitive_load (const char *filename)

scm_primitive_load, but taking a C string instead of an SCM.

Variable: current-reader

current-reader holds the read procedure that is currently being used by the above loading procedures to read expressions (from the file that they are loading). current-reader is a fluid, so it has an independent value in each dynamic root and should be read and set using fluid-ref and fluid-set! (see Fluids and Dynamic States).

Changing current-reader is typically useful to introduce local syntactic changes, such that code following the fluid-set! call is read using the newly installed reader. The current-reader change should take place at evaluation time when the code is evaluated, or at compilation time when the code is compiled:

(eval-when (compile eval)
  (fluid-set! current-reader my-own-reader))

The eval-when form above ensures that the current-reader change occurs at the right time.

Variable: %load-hook

A procedure to be called (%load-hook filename) whenever a file is loaded, or #f for no such call. %load-hook is used by all of the loading functions (load and primitive-load, and load-from-path and primitive-load-path documented in the next section).

For example an application can set this to show what’s loaded,

(set! %load-hook (lambda (filename)
                   (format #t "Loading ~a ...\n" filename)))
(load-from-path "foo.scm")
-| Loading /usr/local/share/guile/site/foo.scm ...

Scheme Procedure: current-load-port

C Function: scm_current_load_port ()

Return the current-load-port. The load port is used internally by primitive-load.