Make readline optional.

* gash/readline.scm: New file.
* build-aux/build-guile.sh: Compile it.
* gash/gash.scm: Use it as fallback.

build-aux/build-guile.sh

@@ -53,6 +53,7 @@ gash/job.scm
 gash/lzw.scm
 gash/peg.scm
 gash/pipe.scm
+gash/readline.scm
 gash/script.scm
 gash/ustar.scm
 gash/util.scm

gash/gash.scm

@@ -9,7 +9,6 @@
   #:use-module (ice-9 local-eval)
   #:use-module (ice-9 match)
   #:use-module (ice-9 rdelim)
-  #:use-module (ice-9 readline)
   #:use-module (ice-9 pretty-print)
   #:use-module (ice-9 receive)
   #:use-module (ice-9 regex)
@@ -30,6 +29,11 @@
             parse
             parse-string))
 
+(catch #t
+  (lambda _ (use-modules (ice-9 readline)))
+  (lambda (key . args)
+    (use-modules (gash readline))))
+
 (define %debug-level 0)       ; 1 informational, 2 verbose, 3 peg tracing
 (define %prefer-builtins? #f) ; use builtin, even if COMMAND is available in PATH?
 (define %geesh-parser? #f)    ; use Geesh parser [EXPERIMENTAL]

gash/readline.scm

@@ -0,0 +1,41 @@
+;;; Gash -- Guile As SHell
+;;; Copyright © 2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+;;;
+;;; This file is part of Gash.
+;;;
+;;; Gash 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.
+;;;
+;;; Gash 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 Gash.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;;; This is a fallback module for the bootstrap guile where (ice-9
+;;; readline) is not available.
+
+;;; Code:
+
+(define-module (gash readline)
+  #:use-module (ice-9 rdelim)
+  #:export (add-history
+            clear-history
+            read-history
+            readline
+            with-readline-completion-function
+            write-history))
+
+(define (add-history x) #t)
+(define (clear-history) #t)
+(define (read-history x) #t)
+(define (readline prompt) (display prompt) (read-line))
+(define (with-readline-completion-function completion thunk) (thunk))
+(define (write-history x) #t)
+