Add readonly built-in

* geesh/built-ins/utils.scm: New file.
* geesh/built-ins/readonly.scm: New file.
* Makefile.am: Add them.
* geesh/built-ins/export.scm (split-assignments): Move to utils.
* geesh/built-ins.scm (*special-built-ins*): Add readonly.

Makefile.am

@@ -47,8 +47,10 @@ MODULES =                                       \
   geesh/built-ins/export.scm                    \
   geesh/built-ins/false.scm                     \
   geesh/built-ins/read.scm                      \
+  geesh/built-ins/readonly.scm                  \
   geesh/built-ins/true.scm                      \
   geesh/built-ins/unset.scm                     \
+  geesh/built-ins/utils.scm                     \
   geesh/built-ins.scm                           \
   geesh/environment.scm                         \
   geesh/eval.scm                                \

geesh/built-ins.scm

@@ -40,7 +40,7 @@
     ("exec" . ,undefined)
     ("exit" . ,undefined)
     ("export" . ,(@@ (geesh built-ins export) main))
-    ("readonly" . ,undefined)
+    ("readonly" . ,(@@ (geesh built-ins readonly) main))
     ("return" . ,undefined)
     ("set" . ,undefined)
     ("shift" . ,undefined)

geesh/built-ins/export.scm

@@ -17,6 +17,7 @@
 ;;; along with Geesh.  If not, see <http://www.gnu.org/licenses/>.
 
 (define-module (geesh built-ins export)
+  #:use-module (geesh built-ins utils)
   #:use-module (geesh environment)
   #:use-module (ice-9 match))
 
@@ -26,14 +27,6 @@
 ;;;
 ;;; Code:
 
-(define (split-assignment assignment)
-  (match (string-index assignment #\=)
-    (#f (values assignment #f))
-    (index (let ((name (substring assignment 0 index)))
-             (match (substring assignment (1+ index))
-               ((? string-null?) (values name #f))
-               (value (values name value)))))))
-
 (define (main env . args)
   (match args
     (("-p") (throw 'not-implemented "export -p"))

geesh/built-ins/readonly.scm

@@ -0,0 +1,38 @@
+;;; The Geesh Shell Interpreter
+;;; Copyright 2018 Timothy Sample <samplet@ngyro.com>
+;;;
+;;; This file is part of Geesh.
+;;;
+;;; Geesh is free software: you can redistribute it and/or modify
+;;; it under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; Geesh is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with Geesh.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (geesh built-ins readonly)
+  #:use-module (geesh built-ins utils)
+  #:use-module (geesh environment)
+  #:use-module (ice-9 match))
+
+;;; Commentary:
+;;;
+;;; The 'readonly' utility.
+;;;
+;;; Code:
+
+(define (main env . args)
+  (match args
+    (("-p") (throw 'not-implemented "readonly -p"))
+    (_ (for-each (lambda (assignment)
+                   (call-with-values (lambda () (split-assignment assignment))
+                     (lambda (name value)
+                       (set-var-read-only! env name value))))
+                 args)
+       0)))

geesh/built-ins/utils.scm

@@ -0,0 +1,35 @@
+;;; The Geesh Shell Interpreter
+;;; Copyright 2018 Timothy Sample <samplet@ngyro.com>
+;;;
+;;; This file is part of Geesh.
+;;;
+;;; Geesh is free software: you can redistribute it and/or modify
+;;; it under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; Geesh is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with Geesh.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (geesh built-ins utils)
+  #:use-module (ice-9 match)
+  #:export (split-assignment))
+
+;;; Commentary:
+;;;
+;;; Utility functions shared by built-ins.
+;;;
+;;; Code:
+
+(define (split-assignment assignment)
+  (match (string-index assignment #\=)
+    (#f (values assignment #f))
+    (index (let ((name (substring assignment 0 index)))
+             (match (substring assignment (1+ index))
+               ((? string-null?) (values name #f))
+               (value (values name value)))))))