[[tags: egg]]

== SRFI 193

[[toc:]]

=== Introduction

This egg implements
[[https://srfi.schemers.org/srfi-193/srfi-193.html|SRFI 193: Command
line]].

=== Documentation

==== Command

<parameter>(command-line [string-list])</parameter>

Like the standard {{command-line}} procedure in R7RS and R6RS, this
gives the command line as list of strings. The first element (always
present) is the command name and the remaining elements (if any) are
command arguments.

Unlike RnRS {{command-line}}, this is a parameter that can be bound to
another value by the Scheme programmer if desired, for example for
subcommand processing.

The value of this parameter should be a list of one or more strings at
all times. Neither the strings nor the list should be mutated. If the
parameter is rebound to another list, the new list is permitted to
share structure with the old list.

The default value of the parameter is more precisely specified than
the value of RnRS {{command-line}}. When evaluating code in the csi
REPL, the command line is a one-element list whose only element is a
zero-length string.

When running a standalone program compiled via csc, the first element
is the operating system's {{argv[0]}} and the remaining elements are
{{argv[1]}} and up. However, any {{-:}} arguments that give options
for the Chicken runtime system are not part of the list.

<procedure>(command-name)</procedure>

Returns a simplified version of {{(car (command-line))}}, respecting
the current binding of the {{command-line}} parameter.

This is typically something suitable to display as the program name.
For example, {{/path/to/foo.scm}} is simplified into {{foo}}.

However, if {{(car (command-line))}} is a zero-length string (such as
at the csi REPL), {{#f}} is returned to signify "not a command".

<procedure>(command-args)</procedure>

Returns {{(cdr (command-line))}}, respecting the current binding of
the {{command-line}} parameter.

==== Script

<parameter>(script-file [string?])</parameter>

If running a Scheme source file in csi, returns an absolute pathname
of that file as a string. Otherwise returns {{#f}}.

In Chicken, this is actually a parameter object and may be set by the
user.

<procedure>(script-directory)</procedure>

Returns {{(script-file)}} without the filename part, respecting the
current binding of the {{script-file}} parameter. Returns {{#f}} in
any situation where {{(script-file)}} returns {{#f}}.

Returned strings end with a directory separator so {{string-append}}
can be used to build pathnames to refer to files in the same directory
as the script.

=== Version History

* 0.1: First release.

=== Author

Lassi Kortela

=== Repository

[[https://github.com/lassik/chicken-srfi-193|https://github.com/lassik/chicken-srfi-193]]

=== License

  Copyright 2020 Lassi Kortela

  Permission to use, copy, modify, and distribute this software for any
  purpose with or without fee is hereby granted, provided that the above
  copyright notice and this permission notice appear in all copies.

  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
  WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
  WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
  AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  PERFORMANCE OF THIS SOFTWARE.