[[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
returns 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. Neither the strings nor the list should be mutated.

Unlike RnRS {{command-line}} this is a parameter that can be bound to
another value, e.g. for subcommand processing. If the parameter is
rebound to another list, the new list may share structure with the old
list.

The initial command line is more precisely specified than the value of
RnRS {{command-line}}:

* When running a standalone program compiled by 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.

* When running a script via {{csi -script file.scm a b c}} or {{csi -s
  file.scm a b c}} then {{command-line}} is bound to {{'("file.scm"
  "a" "b" "c")}}.

* When not running a command, {{command-line}} is bound to {{'("")}}.
  This happens when:

** Loading source files into the {{csi}} REPL via {{csi file.scm}}.
** Loading source files into the {{csi}} REPL via {{(load "file.scm")}}.
** Evaluating code in the {{csi}} REPL.

<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, {{#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 source file as a script via {{csi -script file.scm}} or
{{csi -s file.scm}}, 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.

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

Returns {{#f}} in any situation where {{(script-file)}} returns
{{#f}}.

=== Version History

* 0.1.3: Add Chicken 4 egg
* 0.1.2: Fix tests
* 0.1.1: Fix bug where pre-compiled .so gave incorrect results in {{csi}}
* 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.