feat(output)!: print REAL values in shortest round-trip form

OUTPUT and NUM_TO_STR now share Python repr formatting instead of %f.

BREAKING CHANGE: REAL output changes from six fixed decimals (2.500000) to the shortest round-trip text (2.5).

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

2 files changed, 2 insertions, 2 deletions

diff --git a/doc/language/function/cpsc-function-num_to_str.7.md b/doc/language/function/cpsc-function-num_to_str.7.md
index 39b6890..8e895ee 100644
--- a/doc/language/function/cpsc-function-num_to_str.7.md
+++ b/doc/language/function/cpsc-function-num_to_str.7.md
@@ -14,7 +14,7 @@ NUM_TO_STR(number : INTEGER or REAL) RETURNS STRING
 
 Provided by the standard string library, loaded and linked by default.
 
-Format INTEGER as signed decimal text and REAL with six digits after the decimal point.
+Format INTEGER as signed decimal text and REAL in the same shortest round-trip form that OUTPUT prints. The text is the shortest decimal text that reads back as the same value (as Python's `repr`): fixed notation with at least one fractional digit when 1e-4 <= |x| < 1e16 (`2.0`, `87.5`, `0.0001`), otherwise scientific notation with an exponent of at least two digits (`1e-07`, `1.5e-07`, `1e+16`); special values print as `-0.0`, `inf`, `-inf` and `nan`.
 
 # EXAMPLE
 
diff --git a/doc/language/keyword/cpsc-keyword-output.7.md b/doc/language/keyword/cpsc-keyword-output.7.md
index 06d9910..d115ace 100644
--- a/doc/language/keyword/cpsc-keyword-output.7.md
+++ b/doc/language/keyword/cpsc-keyword-output.7.md
@@ -12,7 +12,7 @@ OUTPUT expression, ...
 
 # DESCRIPTION
 
-Print expressions from left to right without automatic separators, then add a newline. Strings print their contents; BOOLEAN prints TRUE or FALSE. Whole arrays and partially indexed arrays print their elements one per line; a final array adds no extra newline. Other records, classes, and pointers cannot be printed directly.
+Print expressions from left to right without automatic separators, then add a newline. Strings print their contents; BOOLEAN prints TRUE or FALSE. REAL values use the shortest decimal text that reads back as the same value (as Python's `repr`): fixed notation with at least one fractional digit when 1e-4 <= |x| < 1e16 (`2.0`, `87.5`, `0.0001`), otherwise scientific notation with an exponent of at least two digits (`1e-07`, `1.5e-07`, `1e+16`); special values print as `-0.0`, `inf`, `-inf` and `nan`. OUTPUT and NUM_TO_STR produce identical text. Whole arrays and partially indexed arrays print their elements one per line; a final array adds no extra newline. Other records, classes, and pointers cannot be printed directly.
 
 C scalars print with their native type's format and C argument promotions. Plain char prints a character, other C integers print numbers, and _Bool prints TRUE or FALSE. C_STRING is a pointer: cast it to STRING to print its contents. See [cpsc-keyword-c_type(7)](cpsc-keyword-c_type.7.md).