Re: [PATCH] ice-9: Add JSON module.

[Mark H Weaver]

Matt Wette  writes:

> On Sep 21, 2015, at 1:08 PM, Ludovic Courtès  wrote:
>
> 
> David Thompson  skribis:
> 
> JSON is an commonly encountered format when writing web
> applications,
> much like XML, and I think it would be a good idea if the core
> Guile
> distribution had an SXML equivalent for JSON. This patch
> introduces
> such an interface in the (ice-9 json) module.
> 
>
> There’s also guile-json, bindings to a C library, but I think it’s
> better to have a pure Scheme implementation, and to have it in
> Guile
> core.
> 
> I wonder if we should introduce it in 2.0. What do people think?
> 
>
> I would be happy to have this in the core; I have used it.

Agreed.

> 1. There is a minor typo in the source: should be "denominator.”

Indeed, good catch!

> 2. The comments say integers are converted to exact and floating point
> to inexact, but the code will convert 1.0 to exact.

In Scheme terminology, 1.0 is an integer.

> Would it work to use the parser from (language ecmascript parse),
> possibly restricting it? Or do you think it’s more viable to have
> a
> separate parser because there are too many differences?
> 
>
> I vote for separate parser, the json.scm file is lightweight.
> json.scm.go is < 17k.

Agreed.  The simplicity also allows confidence that it can safely handle
potentially malicious JSON data.

  Mark

Re: [PATCH] ice-9: Add JSON module.

[Matt Wette]

> On Sep 21, 2015, at 11:49 PM, Mark H Weaver  wrote:
> 
>> 2. The comments say integers are converted to exact and floating point
>> to inexact, but the code will convert 1.0 to exact.
> 
> In Scheme terminology, 1.0 is an integer.

But in guile-2.0.11:

scheme@(guile-user)> (exact? (string->number "1.0"))
$1 = #f

I also vote for using string->number: probably faster and more heavily tested.

Matt

Re: [PATCH] ice-9: Add JSON module.

[Matt Wette]

> On Sep 21, 2015, at 1:08 PM, Ludovic Courtès  wrote:
> 
> David Thompson  skribis:
> 
>> JSON is an commonly encountered format when writing web applications,
>> much like XML, and I think it would be a good idea if the core Guile
>> distribution had an SXML equivalent for JSON.  This patch introduces
>> such an interface in the (ice-9 json) module.
> 
> There’s also guile-json, bindings to a C library, but I think it’s
> better to have a pure Scheme implementation, and to have it in Guile
> core.
> 
> I wonder if we should introduce it in 2.0.  What do people think?


I would be happy to have this in the core; I have used it.  A few comments:

1. There is a minor typo in the source: should be "denominator.”
2. The comments say integers are converted to exact and floating point to 
inexact, but the code will convert 1.0 to exact.

> Would it work to use the parser from (language ecmascript parse),
> possibly restricting it?  Or do you think it’s more viable to have a
> separate parser because there are too many differences?

I vote for separate parser, the json.scm file is lightweight.  json.scm.go is < 
17k.

Re: [PATCH] ice-9: Add JSON module.

[Ludovic Courtès]

David Thompson  skribis:

> JSON is an commonly encountered format when writing web applications,
> much like XML, and I think it would be a good idea if the core Guile
> distribution had an SXML equivalent for JSON.  This patch introduces
> such an interface in the (ice-9 json) module.

There’s also guile-json, bindings to a C library, but I think it’s
better to have a pure Scheme implementation, and to have it in Guile
core.

I wonder if we should introduce it in 2.0.  What do people think?

> +(define (json-error port)
> +  (throw 'json-error port))

This won’t print correctly, unless there’s an exception printer
installed in boot-9.scm (see ‘getaddrinfo-error’ for instance.)  Could
you add one?

Also, I think we need more details about the error: parse error, what
kind, etc.

Would it work to use the parser from (language ecmascript parse),
possibly restricting it?  Or do you think it’s more viable to have a
separate parser because there are too many differences?

Is there a standard test suite that we could test it against, somehow?

Otherwise LGTM.

Thanks, and sorry for the delay!

Ludo’.

Re: [PATCH] ice-9: Add JSON module.

[Christopher Allan Webber]

I tested this, including with the fixes specified in the email.
(ice-9 json) seems to be working great... I'd love to see it
merged!

Re: [PATCH] ice-9: Add JSON module.

[David Thompson]

Noticed a couple of small issues after I sent the initial patch that
I've fixed in my local git branch:

David Thompson da...@gnu.org writes:

 +(define-module (ice-9 json)
 +  #:use-module (ice-9 match)
 +  #:use-module (srfi srfi-1)
 +  #:export (read-json write-json))

No need to import SRFI-1.

 +(define (read-zeroes port)
 +  Read a sequence of zeroes from PORT.
 +  (let loop ((result '()))
 +(match (peek-char port)
 +  ((? eof-object?)
 +   result)
 +  (#\0
 +   (read-char port)
 +   (loop (cons 0 result)))
 +  (else result

Never used.  Removed.

-- 
David Thompson
GPG Key: 0FF1D807

[PATCH] ice-9: Add JSON module.

[David Thompson]

Hello Guilers,

JSON is an commonly encountered format when writing web applications,
much like XML, and I think it would be a good idea if the core Guile
distribution had an SXML equivalent for JSON.  This patch introduces
such an interface in the (ice-9 json) module.

With (ice-9 json), this expression:

(@ (name . Eva Luator)
   (age . 24)
   (schemer . #t)
   (hobbies hacking cycling surfing))

serializes to this JSON (except not pretty-printed):

{
  name: Eva Luator,
  age: 24,
  schemer: true,
  hobbies: [
hacking,
cycling,
surfing
  ]
}

Thanks to Mark Weaver and Chris Webber for helping come to a consensus
on a good syntax for JSON objects.

From 2d4d8607aedaede98f413a84f135d8798d506233 Mon Sep 17 00:00:00 2001
From: David Thompson dthomps...@worcester.edu
Date: Sat, 15 Aug 2015 14:09:23 -0400
Subject: [PATCH] ice-9: Add JSON module.

* module/ice-9/json.scm: New file.
* module/Makefile.am (ICE_9_SOURCES): Add it.
* test-suite/tests/json.test: New file.
* test-suite/Makefile.am (SCM_TESTS): Add it.
* doc/ref/guile.texi (Guile Modules): Add JSON section.
* doc/ref/json.texi: New file.
* doc/ref/Makefile.am (guile_TEXINFOS): Add it.
---
 doc/ref/Makefile.am|   3 +-
 doc/ref/guile.texi |   2 +
 doc/ref/json.texi  |  62 +++
 module/Makefile.am |   3 +-
 module/ice-9/json.scm  | 395 +
 test-suite/Makefile.am |   1 +
 test-suite/tests/json.test | 149 +
 7 files changed, 613 insertions(+), 2 deletions(-)
 create mode 100644 doc/ref/json.texi
 create mode 100644 module/ice-9/json.scm
 create mode 100644 test-suite/tests/json.test

diff --git a/doc/ref/Makefile.am b/doc/ref/Makefile.am
index 31c26a7..5dfc019 100644
--- a/doc/ref/Makefile.am
+++ b/doc/ref/Makefile.am
@@ -95,7 +95,8 @@ guile_TEXINFOS = preface.texi			\
 		 goops.texi			\
 		 goops-tutorial.texi		\
 		 guile-invoke.texi		\
-		 effective-version.texi
+		 effective-version.texi		\
+		 json.texi
 
 ETAGS_ARGS = $(info_TEXINFOS) $(guile_TEXINFOS)
 
diff --git a/doc/ref/guile.texi b/doc/ref/guile.texi
index db815eb..468d3a5 100644
--- a/doc/ref/guile.texi
+++ b/doc/ref/guile.texi
@@ -375,6 +375,7 @@ available through both Scheme and C interfaces.
 * Statprof::An easy-to-use statistical profiler.
 * SXML::Parsing, transforming, and serializing XML.
 * Texinfo Processing::  Munging documents written in Texinfo.
+* JSON::Parsing and serializing JSON.
 @end menu
 
 @include slib.texi
@@ -397,6 +398,7 @@ available through both Scheme and C interfaces.
 @include statprof.texi
 @include sxml.texi
 @include texinfo.texi
+@include json.texi
 
 @include goops.texi
 
diff --git a/doc/ref/json.texi b/doc/ref/json.texi
new file mode 100644
index 000..43dba4d
--- /dev/null
+++ b/doc/ref/json.texi
@@ -0,0 +1,62 @@
+@c -*-texinfo-*-
+@c This is part of the GNU Guile Reference Manual.
+@c Copyright (C) 2015  Free Software Foundation, Inc.
+@c See the file guile.texi for copying conditions.
+@c
+
+@node JSON
+@section JSON
+
+@cindex json
+@cindex (ice-9 json)
+
+The @code{(ice-9 json)} module provides procedures for parsing and
+serializing JSON, the JavaScript Object Notation data interchange
+format.  For example, the JSON document:
+
+@example
+@verbatim
+{
+  name: Eva Luator,
+  age: 24,
+  schemer: true,
+  hobbies: [
+hacking,
+cycling,
+surfing
+  ]
+}
+@end verbatim
+@end example
+
+may be represented with the following s-expression:
+
+@example
+@verbatim
+(@ (name . Eva Luator)
+   (age . 24)
+   (schemer . #t)
+   (hobbies hacking cycling surfing))
+@end verbatim
+@end example
+
+Strings, real numbers, @code{#t}, @code{#f}, @code{#nil}, lists, and
+association lists may be serialized as JSON.  Association lists
+serialize to objects, and regular lists serialize to arrays.  To
+distinguish regular lists from association lists, the @code{@@} symbol
+is used to ``tag'' the association list as a JSON object, as in the
+above example.  The keys of association lists may be either strings or
+symbols.
+
+@deffn {Scheme Procedure} read-json port
+
+Parse JSON-encoded text from @var{port} and return its s-expression
+representation.
+
+@end deffn
+
+@deffn {Scheme Procedure} write-json exp port
+
+Write the expression @var{exp} as JSON-encoded text to @var{port}.
+
+@end deffn
diff --git a/module/Makefile.am b/module/Makefile.am
index 7e96de7..6380953 100644
--- a/module/Makefile.am
+++ b/module/Makefile.am
@@ -256,7 +256,8 @@ ICE_9_SOURCES = \
   ice-9/list.scm \
   ice-9/serialize.scm \
   ice-9/local-eval.scm \
-  ice-9/unicode.scm
+  ice-9/unicode.scm \
+  ice-9/json.scm
 
 srfi/srfi-64.go: srfi/srfi-64.scm srfi/srfi-64/testing.scm
 
diff --git a/module/ice-9/json.scm b/module/ice-9/json.scm
new file mode 100644
index 000..3850ee4
--- /dev/null
+++ b/module/ice-9/json.scm
@@ -0,0 +1,395