[Pharo-users] Re: JSON without lf?

April 10, 2026

      CLAUDE.ai answer:
  The short answer: use STON toJsonString: obj (no Pretty). It produces compact JSON on a single line with zero line    
  feeds:

  STON toJsonString: (Dictionary new at: 'foo' put: 1; at: 'bar' put: #(1 2 3); yourself)                               
  "=> '{"foo":1,"bar":[1,2,3]}'"               
  Verified byte-level â the output contains no 0x0A (LF) bytes.                                                         

  Why toJsonStringPretty: is flaky for tests. It's a one-liner that delegates to STON jsonWriter with prettyPrint: true.
   The writer's newline character is set in STONWriter>>initialize:                                                     

  newLine := OSPlatform current lineEnding.                                                                             
  So you get LF on macOS/Linux and CRLF on Windows â different expected strings per platform. That's the real source of
  the pain.                                                                                                             

  If you actually want pretty output but deterministic line endings, build the writer yourself and call newLine:        
  explicitly (it takes any string â CR, LF, CRLF, or even ''):                                                          

  String streamContents: [ :out |                                                                                       
      ((STON jsonWriter on: out)    
          prettyPrint: true;                                                                                            
          newLine: String lf;    
          yourself) nextPut: object ]                                                                                   
  STONWriter>>newLine: is a public accessor, and newlineIndent just writes whatever string you set, so passing String 
  cr, String crlf, or '' all work. I confirmed it by reading STONWriter>>newLine:, newlineIndent, and dumping raw bytes 
  from a pretty run with newLine: String cr â got byte 13, no byte 10.                                                 

  So, for test stability, the two clean answers for the pharo list are:

  1. Use `STON toJsonString:` â compact, no newlines, no platform drift.                                                
  2. Or configure the writer: `(STON jsonWriter on: s) prettyPrint: true; newLine: String lf; ...` â pretty, but with a 
  line ending you pick instead of the OS default.                                                                       
  The base image only ships STON for JSON (no NeoJSON installed), so these are the relevant knobs.

----- Original message -----
From: stephane ducasse via Pharo-users <pharo-users@lists.pharo.org>
To: Any question about pharo is welcome <pharo-users@lists.pharo.org>
Cc: stephane ducasse <stephane.ducasse@inria.fr>
Subject: [Pharo-users] JSON without lf?
Date: Friday, April 10, 2026 6:54 AM

Hi 

I would like to know if there is a way to generate JSON without lf?

toJsonStringPretty: is generating lf and this is painful for tests.

S.

[Pharo-users] Re: JSON without lf?

Aaron Wohl