Regular Strings

Regular strings — quoted strings with escape sequences.

A regular string is a sequence of Unicode code points enclosed in single quotes (', U+0027) or double quotes (", U+0022). Regular strings allow any character — including whitespace and structural characters — and support escape sequences for special code points. This makes them suitable for text that needs leading or trailing whitespace, structural characters, or escaping.

Regular strings are scalar values. They preserve all content as written, including whitespace and Unicode characters.

Syntax

A regular string is enclosed in single or double quotes and may contain any Unicode code point, with support for escape sequences.

regularString     = '"' { dqChar | escapeSequenceDQ } '"' | "'" { sqChar | escapeSequenceSQ } "'"
dqChar            = any Unicode code point except '"' or '\'
sqChar            = any Unicode code point except "'" or '\'
escapeSequenceDQ  = '\' ( '"' | "'" | '\' | 'b' | 'f' | 'r' | 'n' | 't' | unicodeEscape | hexEscape | other )
escapeSequenceSQ  = '\' ( "'" | '"' | '\' | 'b' | 'f' | 'r' | 'n' | 't' | unicodeEscape | hexEscape | other )
unicodeEscape     = 'u' hex4
hexEscape         = 'x' hex2
hex4              = 4 hexadecimal digits (must form a valid Unicode code point)
hex2              = 2 hexadecimal digits
other             = any character except 'u' or 'x'

Structural characters

Symbol

Name

Unicode

Description

"

Double quote

U+0022

Encloses the string; must be escaped inside

'

Single quote

U+0027

Encloses the string; must be escaped inside

\

Reverse solidus

U+005C

Escape character

(space, tab, etc.)

Whitespace

Multiple

Preserved as written

Any

Any Unicode code point

Multiple

Allowed, except an unescaped enclosing quote

Valid forms

Examples of valid regular strings:

"John Doe"
'John Doe'
"   John Doe   "                 # leading/trailing whitespace preserved
"Peter D'mello"                  # single quote needs no escape in a double-quoted string
'Peter D\'mello'                 # escaped single quote in a single-quoted string
"जॉन डो"
'Can contain unicode characters 😃'
"She said, \"I Love it\""        # escaped double quotes
'She said, "I Love it"'          # double quotes need no escape in a single-quoted string
"Line one\nLine two"             # \n is interpreted as a newline
"\x3A"                           # two-digit hex escape -> ":"
"\u00AF"                         # four-digit unicode escape -> "¯"
"\uD83D\uDE00"                   # UTF-16 surrogate pair -> "😀"

Optional behaviors

Whitespace — leading, trailing, and internal whitespace are preserved.
Escaping — only these escape sequences are interpreted: \n, \", \\, \', \b, \f, \r, \t, \u (exactly 4 hex digits, forming a valid code point), and \x (exactly 2 hex digits). For any other sequence (e.g. \o), the backslash is dropped and the following character is kept literally — so "hell\o" emits hello.
Multiline — newline and carriage-return characters are preserved.
Equivalence — escaped and unescaped forms are equal when they represent the same code points.

Comments

Comments are not allowed inside regular strings, but may appear outside or between values, per the format's comment rules.

Invalid forms

"John Doe                 # ✗ unterminated-string — missing closing quote
"She said, "I Love it""   # ✗ unexpected-token — unescaped inner quote

Unquoted text is not an error at all — it is an open string, which is exactly why quoting is optional:

---
John Doe                  # → "John Doe", an open string

Lenient escapes. An unrecognized escape such as \q is not an error — the backslash is dropped and the character is kept, so "\q" emits q. The genuine errors above are an unquoted value, an unterminated string, and an unescaped enclosing quote.

Preservation of structure

Internet Object preserves:

All Unicode code points and whitespace as written
Escaped and unescaped forms (syntactic fidelity)

It does not interpret or enforce:

Application-specific constraints
Normalization of escape sequences beyond equivalence