Make the R6RS simple I/O library use conditions

* module/rnrs/io/ports.scm (display): Implement as an
  exception-converting wrapper around Guile's core display.
* module/rnrs/io/simple.scm: Don't export Guile's corresponding core
  procedures, but use `(rnrs io ports)' instead.  This way, we get the
  conditions required by R6RS raised.

* doc/ref/r6rs.texi (rnrs io simple): Mention that these procedures are
  supposed to raise R6RS conditions.

doc/ref/r6rs.texi

@@ -1428,8 +1428,21 @@ functionality is documented in its own section of the manual;
 
 The @code{(rnrs io simple (6))} library provides convenience functions
 for performing textual I/O on ports.  This library also exports all of
-the condition types and associated procedures described in
+the condition types and associated procedures described in (@pxref{I/O
-(@pxref{I/O Conditions}).
+Conditions}).  In the context of this section, when stating that a
+procedure behaves ``identically'' to the corresponding procedure in
+Guile's core library, this is modulo the behavior wrt. conditions: such
+procedures raise the appropriate R6RS conditions in case of error, but
+otherwise behave identically.
+
+@c FIXME: remove the following note when proper condition behavior has
+@c been verified.
+
+@quotation Note
+There are still known issues regarding condition-correctness; some
+errors may still be thrown as native Guile exceptions instead of the
+appropriate R6RS conditions.
+@end quotation
 
 @deffn {Scheme Procedure} eof-object
 @deffnx {Scheme Procedure} eof-object? obj

module/rnrs/io/ports.scm

@@ -110,7 +110,9 @@
           (rnrs files) ;for the condition types
           (srfi srfi-8)
           (ice-9 rdelim)
-          (except (guile) raise))
+          (except (guile) raise display)
+          (prefix (only (guile) display)
+                  guile:))
 
 
 
@@ -377,6 +379,12 @@ return the characters accumulated in that port."
          (else
           (display s port)))))
 
+;; Defined here to be able to make use of `with-i/o-encoding-error', but
+;; not exported from here, but from `(rnrs io simple)'.
+(define* (display object #:optional (port (current-output-port)))
+  (with-i/o-encoding-error
+    (guile:display object port)))
+
 
 ;;;
 ;;; Textual input.

module/rnrs/io/simple.scm

@@ -1,6 +1,6 @@
 ;;; simple.scm --- The R6RS simple I/O library
 
-;;      Copyright (C) 2010 Free Software Foundation, Inc.
+;;      Copyright (C) 2010, 2011 Free Software Foundation, Inc.
 ;;
 ;; This library is free software; you can redistribute it and/or
 ;; modify it under the terms of the GNU Lesser General Public
@@ -85,42 +85,76 @@
 
   (import (only (rnrs io ports)
                 call-with-port
+                close-port
                 open-file-input-port
                 open-file-output-port
                 eof-object 
-                eof-object? 
+                eof-object?
-                
+                file-options
+                native-transcoder
+                get-char
+                lookahead-char
+                get-datum
+                put-char
+                put-datum
+
                 input-port? 
                 output-port?)
-          (only (guile) @@
+          (only (guile)
-			current-input-port
+                @@
-			current-output-port
+                current-input-port
-			current-error-port
+                current-output-port
+                current-error-port
 
-			with-input-from-file
+                define*
-			with-output-to-file
 
-			open-input-file
+                with-input-from-port
-			open-output-file
+                with-output-to-port)
-			
-			close-input-port
-			close-output-port
-
-			read-char
-			peek-char
-			read
-			write-char
-			newline
-			display
-			write)
 	  (rnrs base (6))
           (rnrs files (6)) ;for the condition types
           )
 
+  (define display (@@ (rnrs io ports) display))
+
   (define (call-with-input-file filename proc)
     (call-with-port (open-file-input-port filename) proc))
 
   (define (call-with-output-file filename proc)
     (call-with-port (open-file-output-port filename) proc))
-  
+
-)
+  (define (with-input-from-file filename thunk)
+    (call-with-input-file filename
+      (lambda (port) (with-input-from-port port thunk))))
+
+  (define (with-output-to-file filename thunk)
+    (call-with-output-file filename
+      (lambda (port) (with-output-to-port port thunk))))
+
+  (define (open-input-file filename)
+    (open-file-input-port filename (file-options) (native-transcoder)))
+
+  (define (open-output-file filename)
+    (open-file-output-port filename (file-options) (native-transcoder)))
+
+  (define close-input-port close-port)
+  (define close-output-port close-port)
+
+  (define* (read-char #:optional (port (current-input-port)))
+    (get-char port))
+
+  (define* (peek-char #:optional (port (current-input-port)))
+    (lookahead-char port))
+
+  (define* (read #:optional (port (current-input-port)))
+    (get-datum port))
+
+  (define* (write-char char #:optional (port (current-output-port)))
+    (put-char port char))
+
+  (define* (newline #:optional (port (current-output-port)))
+    (put-char port #\newline))
+
+  (define* (write object #:optional (port (current-output-port)))
+    (put-datum port object))
+
+  )