Summary
A string whose value is exactly the two characters [] is coerced to an empty list instead of staying a Text value. Other bracket-containing strings (even "[1, 2]") are unaffected, so the trigger is very narrow: a string equal to a valid empty-list literal.
Minimal reproduction
store a as "[]"
display "expected Text, got: " with typeof of a
store b as "[1, 2]"
display "for contrast, [1, 2] is: " with typeof of b
Actual output:
expected Text, got: List
for contrast, [1, 2] is: Text
Expected output:
expected Text, got: Text
for contrast, [1, 2] is: Text
The same coercion happens when the value "[]" is produced at runtime, e.g. by substring or by with concatenation ("" with "[" with "" with "]" yields a List), and when returned from an action.
Impact
Any code that legitimately produces the string "[]" — e.g. a templating engine rendering an empty JSON array, or string-building that happens to form [] — gets a list value where a string is expected, leading to downstream type errors or silent wrong output. It's rare (surrounding content avoids it) but surprising and hard to diagnose.
Environment
wfl built from source at current main- rustc 1.94.1, cargo 1.94.1, Linux
Notes
Quoted string literals should never be reinterpreted as list literals. The parse/eval of a Text whose contents look like a collection literal should be independent of the string's characters.
Summary
A string whose value is exactly the two characters
[]is coerced to an empty list instead of staying aTextvalue. Other bracket-containing strings (even"[1, 2]") are unaffected, so the trigger is very narrow: a string equal to a valid empty-list literal.Minimal reproduction
Actual output:
Expected output:
The same coercion happens when the value
"[]"is produced at runtime, e.g. bysubstringor bywithconcatenation ("" with "[" with "" with "]"yields aList), and when returned from an action.Impact
Any code that legitimately produces the string
"[]"— e.g. a templating engine rendering an empty JSON array, or string-building that happens to form[]— gets a list value where a string is expected, leading to downstream type errors or silent wrong output. It's rare (surrounding content avoids it) but surprising and hard to diagnose.Environment
wflbuilt from source at currentmainNotes
Quoted string literals should never be reinterpreted as list literals. The parse/eval of a
Textwhose contents look like a collection literal should be independent of the string's characters.