[PATCH] Adding SRFI-97 support

[PATCH] Adding SRFI-97 support

[Freja Nordsiek]

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Wrote a patch to add SRFI-97 (
https://srfi.schemers.org/srfi-97/srfi-97.html ) support, which allows
SRFIs to be imported as

    (use-modules ((srfi :XX)))
    (import (srfi :XX))

in addition to

    (use-modules ((srfi srfi-XX)))
    (import (srfi srfi-XX))

The SRFI is meant as a way to provide a portable way to import SRFI libraries.

There is one problem, though. If the scheme reader option keywords is
set to 'prefix, SRFI libraries cannot be imported in SRFI-97 style
till it is turned off or to 'postfix. This happens because SRFI-97
isn't implemented as a macro. Instead it is implemented inside the
resolve-module procedure.

Patch includes tests as well as documentation (including the note that
setting the keywords option to 'prefix prevents it from working).


Freja Nordsiek

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From 4c521cbd3e805ebb93e521ebea7234d797152a53 Mon Sep 17 00:00:00 2001
From: Freja Nordsiek <fnordsie@gmail.com>
Date: Tue, 28 Mar 2017 01:56:39 +0200
Subject: [PATCH] Added SRFI-97.

* module/ice-9/boot-9.scm (resolve-module): Added SRFI-97 library name
  aliasing.
* module/ice-9/boot-9.scm (%cond-expand-features): Added SRFI-97
* test-suite/tests/srfi-97.test: Added tests for SRFI-97
* test-suite/Makefile: Included new tests.
* doc/ref/srfi-modules.texi: Added SRFI-97 documentation
* doc/ref/api-modules.texi: Added SRFI-97 information to module import
  documentation
* doc/ref/api-data.texi: Added note that keywords 'prefix and SRFI-97 do not
  work together.
* doc/ref/api-evaluation.texi: Added note that keywords 'prefix and SRFI-97 do
  not work together.
---
 doc/ref/api-data.texi         |  4 +++-
 doc/ref/api-evaluation.texi   |  4 +++-
 doc/ref/api-modules.texi      |  8 +++++++-
 doc/ref/srfi-modules.texi     | 37 ++++++++++++++++++++++++++++++++++---
 module/ice-9/boot-9.scm       | 21 +++++++++++++++++++--
 test-suite/Makefile.am        |  1 +
 test-suite/tests/srfi-97.test | 28 ++++++++++++++++++++++++++++
 7 files changed, 95 insertions(+), 8 deletions(-)
 create mode 100644 test-suite/tests/srfi-97.test

diff --git a/doc/ref/api-data.texi b/doc/ref/api-data.texi
index 214c6e2..33b11b0 100644
--- a/doc/ref/api-data.texi
+++ b/doc/ref/api-data.texi
@@ -5410,7 +5410,9 @@ keywords are self-quoting objects.
 
 If the @code{keywords} read option is set to @code{'prefix}, Guile also
 recognizes the alternative read syntax @code{:NAME}.  Otherwise, tokens
-of the form @code{:NAME} are read as symbols, as required by R5RS.
+of the form @code{:NAME} are read as symbols, as required by R5RS.  Note
+that this option prevents SRFI-97 style SRFI library references from
+working (@pxref{SRFI-97}).
 
 @cindex SRFI-88 keyword syntax
 
diff --git a/doc/ref/api-evaluation.texi b/doc/ref/api-evaluation.texi
index 202ebdc..f397e4b 100644
--- a/doc/ref/api-evaluation.texi
+++ b/doc/ref/api-evaluation.texi
@@ -355,7 +355,9 @@ Similarly, the @code{#!curly-infix} reader directive sets the
 @code{curly-infix} read option on the port, and
 @code{#!curly-infix-and-bracket-lists} sets @code{curly-infix} and
 unsets @code{square-brackets} on the port (@pxref{SRFI-105}).  There is
-currently no other way to access or set the per-port read options.
+currently no other way to access or set the per-port read options.  Note
+that setting @code{keywords} to @code{'prefix} prevents SRFI-97 style SRFI
+library references from working (@pxref{SRFI-97}).
 
 The boolean options may be toggled with @code{read-enable} and
 @code{read-disable}. The non-boolean @code{keywords} option must be set
diff --git a/doc/ref/api-modules.texi b/doc/ref/api-modules.texi
index 8f18b1e..aea75a8 100644
--- a/doc/ref/api-modules.texi
+++ b/doc/ref/api-modules.texi
@@ -174,6 +174,10 @@ Note that just as with a @code{use-modules} statement, any module that
 has not yet been loaded will be loaded when referenced by a @code{@@} or
 @code{@@@@} form.
 
+Note that SRFI libraries can be referred to as @code{(srfi srfi-@var{number})}
+or @code{(srfi :@var{number})}, where @var{number} is the number of the SRFI
+needed.  @xref{SRFI-97}, for documentation of the latter form.
+
 You can also use the @code{@@} and @code{@@@@} syntaxes as the target
 of a @code{set!} when the binding refers to a variable.
 
@@ -846,7 +850,9 @@ been defined and @var{autoload} is true, try to auto-load it.  When it
 can't be found that way either, create an empty module if @var{ensure}
 is true, otherwise return @code{#f}.  If @var{version} is true, ensure
 that the resulting module is compatible with the given version reference
-(@pxref{R6RS Version References}).  The name is a list of symbols.
+(@pxref{R6RS Version References}).  The name is a list of symbols.  Note
+that this procedure allows the usage of SRFI-97 style SRFI references
+(@pxref{SRFI-97}).
 @end deffn
 
 @deffn {Scheme Procedure} resolve-interface name [#:select=#f] @
diff --git a/doc/ref/srfi-modules.texi b/doc/ref/srfi-modules.texi
index f712944..16e9f65 100644
--- a/doc/ref/srfi-modules.texi
+++ b/doc/ref/srfi-modules.texi
@@ -60,6 +60,7 @@ get the relevant SRFI documents from the SRFI home page
 * SRFI-69::                     Basic hash tables.
 * SRFI-87::                     => in case clauses.
 * SRFI-88::                     Keyword objects.
+* SRFI-97::                     Standardized way to reference SRFI libraries.
 * SRFI-98::                     Accessing environment variables.
 * SRFI-105::                    Curly-infix expressions.
 * SRFI-111::                    Boxes.
@@ -81,8 +82,11 @@ There are several reasons for this inconsistency.  First, the feature
 checking syntactic form @code{cond-expand} (@pxref{SRFI-0}) must be
 available immediately, because it must be there when the user wants to
 check for the Scheme implementation, that is, before she can know that
-it is safe to use @code{use-modules} to load SRFI support modules.  The
-second reason is that some features defined in SRFIs had been
+it is safe to use @code{use-modules} to load SRFI support modules.
+Second, the feature to reference SRFI libraries using the syntax
+@code{(srfi :@var{number})} needs to be immediately available to
+facilitate importing SRFI modules using it (@pxref{SRFI-97}).  The
+third reason is that some features defined in SRFIs had been
 implemented in Guile before the developers started to add SRFI
 implementations as modules (for example SRFI-13 (@pxref{SRFI-13})).  In
 the future, it is possible that SRFIs in the core library might be
@@ -94,7 +98,8 @@ you want, you can do that already.  We have included the module
 but ensures that you can write future-safe code.
 
 Generally, support for a specific SRFI is made available by using
-modules named @code{(srfi srfi-@var{number})}, where @var{number} is the
+modules named @code{(srfi srfi-@var{number})} or
+@code{(srfi :@var{number})}, where @var{number} is the
 number of the SRFI needed.  Another possibility is to use the command
 line option @code{--use-srfi}, which will load the necessary modules
 automatically (@pxref{Invoking Guile}).
@@ -165,6 +170,7 @@ srfi-55
 srfi-61
 srfi-62
 srfi-87
+srfi-97
 srfi-105
 @end example
 
@@ -5457,6 +5463,31 @@ Return the keyword object whose name is @var{str}.
 @end example
 @end deffn
 
+@node SRFI-97
+@subsection SRFI-97 - Alternative way to import SRFI libraries
+@cindex SRFI-97
+
+This SRFI lets a Scheme program import SRFI libraries in a portable fashion
+across implementations by referencing them like @code{(srfi :@var{number})},
+where @var{number} is the number of the SRFI needed.  To import SRFI-1
+this way,
+
+@example
+(use-modules ((srfi :1)))
+@end example
+
+or
+
+@example
+(import (srfi :1))
+@end example
+
+This module is loaded by default.
+
+Note that this syntax for referring to SRFI libraries does not work if the
+@code{keywords} read option is set to @code{'prefix}
+(@pxref{Keyword Read Syntax}).
+
 @node SRFI-98
 @subsection SRFI-98 Accessing environment variables.
 @cindex SRFI-98
diff --git a/module/ice-9/boot-9.scm b/module/ice-9/boot-9.scm
index 2777672..df5ec26 100644
--- a/module/ice-9/boot-9.scm
+++ b/module/ice-9/boot-9.scm
@@ -2696,8 +2696,24 @@ deterministic."
     ;; Define the-root-module as '(guile).
     (module-define-submodule! root 'guile the-root-module)
 
-    (lambda* (name #:optional (autoload #t) (version #f) #:key (ensure #t))
-      (let ((already (nested-ref-module root name)))
+    (lambda* (name-unproc #:optional (autoload #t) (version #f) #:key (ensure #t))
+      ;; Implement SRFI-97 by first converting module names of the form
+      ;; ('srfi ':XXXXX ...) to ('srfi 'srfi-XXXXX) where X are base 10 digits.
+      (let* ((name (if (and (list? name-unproc) (not (null? name-unproc))
+                            (not (null? (cdr name-unproc)))
+                            (equal? 'srfi (car name-unproc))
+                            (let ((s (symbol->string (cadr name-unproc)))
+                                  (digits (string->char-set "0123456789")))
+                              (and (string-prefix? ":" s)
+                                   (> (string-length s) 1)
+                                   (string-every (lambda (c) (char-set-contains? digits c))
+                                                 (substring s 1)))))
+                       (list 'srfi
+                             (string->symbol (string-append
+                                              "srfi-"
+                                              (substring (symbol->string (cadr name-unproc)) 1))))
+                       name-unproc))
+             (already (nested-ref-module root name)))
         (cond
          ((and already
                (or (not autoload) (module-public-interface already)))
@@ -3895,6 +3911,7 @@ when none is available, reading FILE-NAME with READER."
     srfi-61  ;; general cond clause
     srfi-62  ;; s-expression comments
     srfi-87  ;; => in case clauses
+    srfi-97  ;; allow SRFI library references to take the form (srfi :XXXX)
     srfi-105 ;; curly infix expressions
     ))
 
diff --git a/test-suite/Makefile.am b/test-suite/Makefile.am
index 3ce9070..793af52 100644
--- a/test-suite/Makefile.am
+++ b/test-suite/Makefile.am
@@ -156,6 +156,7 @@ SCM_TESTS = tests/00-initial-env.test		\
 	    tests/srfi-67.test			\
 	    tests/srfi-69.test			\
 	    tests/srfi-88.test			\
+	    tests/srfi-97.test			\
 	    tests/srfi-98.test			\
 	    tests/srfi-105.test			\
 	    tests/srfi-111.test			\
diff --git a/test-suite/tests/srfi-97.test b/test-suite/tests/srfi-97.test
new file mode 100644
index 0000000..c9ccf00
--- /dev/null
+++ b/test-suite/tests/srfi-97.test
@@ -0,0 +1,28 @@
+;;;; srfi-97.test --- Test suite for importing SRFIs using (srfi :number)
+;;;;
+;;;; Copyright (C) 2017 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
+;;;; License as published by the Free Software Foundation; either
+;;;; version 3 of the License, or (at your option) any later version.
+;;;;
+;;;; This library 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
+;;;; Lesser General Public License for more details.
+;;;;
+;;;; You should have received a copy of the GNU Lesser General Public
+;;;; License along with this library; if not, write to the Free Software
+;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+
+(define-module (test-srfi-97)
+  #:use-module (test-suite lib)
+  #:use-module (srfi srfi-1))
+
+(define (to-bool x) (if x #t #f))
+
+(with-test-prefix "SRFI-97"
+  (pass-if "in cond-expand" (to-bool (find (lambda (x) (eq? 'srfi-97 x)) %cond-expand-features)))
+  (pass-if "use-modules" (to-bool (and (use-modules ((srfi :19))) (current-time time-utc))))
+  (pass-if "import" (to-bool (and (import (srfi :60)) (bitwise-not 2)))))
-- 
2.9.3