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When MIT Scheme is started, the current working
directory (or simply, working directory) is initialized in an
operating-system dependent manner; usually, it is the directory in which
Scheme was invoked. The working directory can be determined from within
Scheme by calling the pwd procedure, and changed by calling the
cd procedure. Each REP loop has its own working directory,
and inferior REP loops initialize their working directory from the
value in effect in their superior at the time they are created.
procedure+: working-directory-pathname
Returns the current working directory as a pathname that has no name,
type, or version components, just host, device, and directory
components. pwd is an alias for
working-directory-pathname; the long name is intended for
programs and the short name for interactive use.
procedure+: set-working-directory-pathname! filename
Makes filename the current working directory and returns the new
current working directory as a pathname. Filename is coerced to a
pathname using pathname-as-directory. cd is an alias for
set-working-directory-pathname!; the long name is intended for
programs and the short name for interactive use.
Additionally, set-working-directory-pathname! modifies the value
of *default-pathname-defaults* by merging the new working
directory into it.
When this procedure is executed in the top-level REP loop, it changes the working directory of the running Scheme executable.
(set-working-directory-pathname! "/usr/morris/blisp")
=> #[pathname "/usr/morris/blisp/"]
(set-working-directory-pathname! "~")
=> #[pathname "/usr/morris/"]
This procedure signals an error if filename does not refer to an existing directory.
If filename describes a relative rather than absolute pathname, this procedure interprets it as relative to the current working directory, before changing the working directory.
(working-directory-pathname)
=> #[pathname "/usr/morris/"]
(set-working-directory-pathname! "foo")
=> #[pathname "/usr/morris/foo/"]
procedure+: with-working-directory-pathname filename thunk
This procedure temporarily rebinds the current working directory to
filename, invokes thunk (a procedure of no arguments), then
restores the previous working directory and returns the value yielded by
thunk. Filename is coerced to a pathname using
pathname-as-directory. In addition to binding the working
directory, with-working-directory-pathname also binds the
variable *default-pathname-defaults*, merging the old value of
that variable with the new working directory pathname. Both bindings
are performed in exactly the same way as dynamic binding of a variable
(see section Dynamic Binding).
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