yarec / s7sh

A shell from s7 Scheme? A shell from s7 Scheme!

A shell from s7 Scheme? A shell from s7 Scheme!

I took the s7 code because I love the presentation page (light style, good content) and the binding of C language. It is in the hope to write my shell (as bash, zsh, ...) with the Scheme language. It is an early version which can break the original code.

first steps: REPL

The big work is a REPL version with a full configuration thanks to files or command line options. Because I am not Windows friendly, all the work is done on Linux and (later) BSD systems. Here is what is working.

compilation

There is a Makefile for the GNU version of make (gmake on BSD systems). The targets are the following:

• all: compile repl-s7,
• clean: delete all the compilation products,
• install: install all that stuff in /usr/local (or elsewhere after editing the PREFIX variable), not implemented today,
• full-clean: call the clean target and remove all object files and dynamic libraries created by running repl-s7,
• test and test-load are deprecated tests.

configuration file(s)

mid October 2019 : There is only one configuration file, ~/.shs7.scm, which must be filled by the user. It is loaded only in interactive mode (see modes below). There is one sample in the s7 directory.

command line arguments

help and version

The first flag to know is -h which show this help and exits:

repl-s7 [-h|-v|-qb] [-L dir-lib] [files ...]
  -h: show this text and exits
  -v: show VERSION and exits
  -q: quiet, suppress some messages
  -b: batch, executes files and quit, implies -q
  -L dir-lib: add dir-lib to *load-path*

The second one is -v which shows the version:

repl-s7 VERSION v0.0.2 (Oct 15 2019 - 16:09:08)

modes

repl-s7 runs in two modes:

• interactive, where you can enter Scheme code at the prompt,
• batch, in which the files of the command line are executed and the interpreter quits at the end of the execution of all files.

interactive mode

Without arguments, repl-s7 loads some libraries, the configuration file(s)and start in interactive mode:

$ ./repl-s7
repl-s7 VERSION v0.0.2 (Oct 15 2019 - 16:09:08)
<1>

You can add some files:

$  ./repl-s7 more-tests/fact.scm
loading more-tests/fact.scm...
repl-s7 VERSION v0.0.2 (Oct 15 2019 - 16:09:08)
<1> (load "more-tests/show-facts.scm")
error: require: no autoload info for fact.scm
<2> (autoload 'fact.scm "fact.scm")
"fact.scm"
<3> (load "more-tests/show-facts.scm")
15! = 1307674368000
14! = 87178291200
13! = 6227020800
...
 2! = 2
 1! = 1
#<unspecified>
<4> 

You can add some library path with one or more -L dirname options.