add JSON5 support by payneca · Pull Request #185 · becls/swish

payneca · 2026-03-30T11:18:19Z

Fixes

fixed an issue where reading a JSON string immediately after a failure to read a string resulted in incorrect output.
fixed an issue where reading a JSON float with a large exponent consumed CPU.

Proposed changes

require Chez Scheme 10.3.0; drop 9.6.4
breaking: change representation of JSON null from the character #\nul to the symbol null
breaking: change JSON read and write functions to use options
This introduces new json:read-options and json:write-options.
custom-inflate is now the inflate-object field of json:read-options.
custom-write is now the custom-write field of json:write-options.
breaking: move stack->json and json-stack->string to json.ss
Code that used (import (swish log-db)) may now need (import (swish json)) to access these procedures.
A new json5? option allows disabling JSON5 support. By default JSON5 is enabled.
A new inflate-symbol option allows raw symbols in JSON-like input to be internalized using a custom function.
A new extended-identifiers? option allows raw symbols in JSON-like input to include characters not allowed by the JSON5 identifier syntax.
split JSON documentation into a separate chapter
export json:key=?

… null

burgerrg · 2026-04-01T13:43:14Z

Now that we don't support Chez 9.6, we should be able to shrink src/swish/compat.ss and possibly move the definitions elsewhere.

burgerrg · 2026-04-01T13:44:13Z

In src/swish/software-info.ss, we no longer need to check (top-level-bound? 'scheme-pre-release).

burgerrg

I've reviewed the documentation and like the changes!

burgerrg · 2026-04-01T20:49:22Z

Please update .github/workflows/test.yml to use actions/checkout@v6.

burgerrg · 2026-04-03T15:05:03Z

src/swish/swish-build.ms has comments about 9.5.3 error messages. These can be removed now.

burgerrg · 2026-04-03T19:20:02Z

On line 1386 of erlang.tex, we find:
\var{max-depth} and stops if recognizes a \code{limit-stack} frame.

It should say:
\var{max-depth} and stops if it recognizes a \code{limit-stack} frame.

burgerrg · 2026-04-06T19:11:16Z

+                (string-escape ip op))
+            (unexpected-input 'string (read-char ip) ip))
+        (read-string ip op mark json5?)]
+       [(char<=? c #\x1F)


I think JSON5 allows control characters to be unescaped.

burgerrg · 2026-04-06T20:40:21Z

A micro-benchmark on my laptop indicates that performing a generic hashtable-ref costs ~20 ns, whereas a symbol-hashtable-ref costs ~10 ns. Switching (swish json) to use symbol hash tables roughly doubles the speed of lookups. We go from 30 ns/call to 15 ns/call.

(define json-object (json:make-object [a #t]))

(define (read-json)
  (json:ref json-object 'a #f))

(define (go f)
  (let lp ([n 1000000])
    (unless (#3%fx<= n 0)
      (f)
      (lp (#3%fx- n 1)))))

> (time (go read-json))
(time (go read-json))
    no collections
    0.030847666s elapsed cpu time
    0.031175000s elapsed real time
    8208 bytes allocated
> (exit)
% git stash apply # To use symbol-hashtable
[...]
> (time (go read-json))
(time (go read-json))
    no collections
    0.015209624s elapsed cpu time
    0.015393000s elapsed real time
    3840 bytes allocated

P.S. The allocation appears to occur in other Swish processes, not the benchmark.

burgerrg · 2026-04-07T14:49:42Z

I think all the uses of zero? in json.ss are used on exact numbers, so it would be more efficient to use (eqv? x 0).

burgerrg

Thanks for this detailed update!

This introduces new json:read-options and json:write-options. custom-inflate is now the inflate-object field of json:read-options

- remove (swish compat); move no-inline into erlang.ss - redefine make-codec-buffer, print-extended-identifiers, print-subnormal-precision, transcoded-port-buffer-size - update all github actions

payneca · 2026-04-09T15:48:50Z

Thanks for the review Bob!

payneca added 4 commits February 27, 2026 15:56

fix: issue reading JSON string after a failure

839122d

fix: issue reading JSON float with large exponent

1d8f12c

split JSON documentation into a separate chapter

488685b

breaking: change representation of JSON null from #\nul to the symbol…

b02c22c

… null

laqrix requested a review from burgerrg March 30, 2026 11:19

burgerrg reviewed Apr 1, 2026

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Comment thread src/swish/erlang.ss

Comment thread src/swish/erlang.ss

Comment thread src/swish/erlang.ss Outdated

Comment thread doc/swish/json.tex Outdated

Comment thread doc/swish/json.tex Outdated

Comment thread doc/swish/json.tex Outdated

payneca force-pushed the cpayne/json branch 2 times, most recently from 4c3d868 to 07dbc08 Compare April 2, 2026 14:33

burgerrg reviewed Apr 3, 2026

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Comment thread doc/reference.bib Outdated

Comment thread src/swish/errors.ss

Comment thread src/swish/software-info.ss Outdated

burgerrg reviewed Apr 3, 2026

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Comment thread src/swish/json.ss Outdated

Comment thread src/swish/json.ss Outdated

Comment thread src/swish/json.ss

Comment thread src/swish/json.ss

burgerrg reviewed Apr 3, 2026

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Comment thread src/swish/json.ss

Comment thread src/swish/json.ss Outdated

burgerrg reviewed Apr 6, 2026

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Comment thread src/swish/json.ss Outdated

burgerrg reviewed Apr 6, 2026

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payneca force-pushed the cpayne/json branch 4 times, most recently from adbde9b to b3694b0 Compare April 8, 2026 13:47

burgerrg approved these changes Apr 8, 2026

View reviewed changes

payneca added 2 commits April 8, 2026 14:04

breaking: change JSON read and write functions to use options

78935b3

This introduces new json:read-options and json:write-options. custom-inflate is now the inflate-object field of json:read-options

breaking: move stack->json and json-stack->string to json.ss

9fac5fd

payneca force-pushed the cpayne/json branch from 4ad8b95 to f439846 Compare April 9, 2026 15:14

payneca added 2 commits April 9, 2026 11:23

require Chez Scheme 10.3.0; drop 9.6.4

8856bf5

- remove (swish compat); move no-inline into erlang.ss - redefine make-codec-buffer, print-extended-identifiers, print-subnormal-precision, transcoded-port-buffer-size - update all github actions

add JSON5 support

6866311

payneca added 2 commits April 9, 2026 11:23

json: add inflate-symbol option

7dc2361

json: add extended-identifiers? option

d44bb43

payneca force-pushed the cpayne/json branch from f439846 to d44bb43 Compare April 9, 2026 15:47

payneca merged commit d44bb43 into becls:dev Apr 9, 2026

payneca deleted the cpayne/json branch April 9, 2026 15:49

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payneca commented Mar 30, 2026

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payneca commented Apr 9, 2026

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