Syntax Reference

Complete reference for the current ASUN text syntax.

Document Shapes

Single row:

{id@int, name@str}:(1, Alice)

Multiple rows:

[{id@int, name@str}]:
  (1, Alice),
  (2, Bob)

The schema appears before :. Data appears after : as one or more tuples.

Schema

Field syntax

{id, name, active}
{id@int, name@str, active@bool}

In text ASUN, @ is the field binding marker. Scalar hints are optional. When present, the only scalar names are:

• int
• float
• str
• bool

For complex fields, the same @ marker is a required structural binding:

• @{...} nested struct
• @[type] array
• @[{...}] array of structs

Examples:

{profile@{id@int, name@str}}
{tags@[str]}
{attrs@[{key@str, value@str}]}

id and id@int are layout-equivalent, but profile@{...} and tags@[...] must keep @ so the parser can see the nested structure boundary.

Field names

Simple names may be unquoted:

{id, name, active}

Quoted field names are required when a field name:

• contains spaces
• starts with digits
• contains syntax characters such as { } [ ] @ "

{"id uuid"@int, "65"@bool, "{}[]@\""@str}

Data

Data is positional. Values follow schema order.

{id@int, name@str, active@bool}:(1, Alice, true)

For nested structs, data is written as nested tuples:

{user@{id@int, name@str}}:((1, Alice))

Inline object literals are not part of the current format.

Scalars

int

42
-7
0

float

3.14
-0.5
1e10

bool

true
false

null / optional

An empty slot means null / absent:

{id@int, label@str}:(1, )

Strings

Unquoted strings

Unquoted strings are allowed for simple values:

Alice
hello world

Rules:

• outer whitespace is trimmed
• reserved syntax characters should be quoted instead
• if a value contains @, quote it to avoid confusion with schema syntax

{name@str}:("@Alice")

Quoted strings

Use quotes when you need to preserve whitespace or include reserved characters:

"value with, comma"
"  leading spaces  "
"line\nbreak"

Supported escapes include \", \\, \n, \t, and \r.

Arrays

[{name@str, scores@[int]}]:
  (Alice, [90, 85, 92]),
  (Bob,   [76, 88])

Nested arrays are also allowed:

[{matrix@[[int]]}]:
  ([[1, 2], [3, 4]])

Entry Lists

Write keyed collections as entry lists:

[{name@str, attrs@[{key@str, value@int}]}]:
  (Alice, [(age, 30), (score, 95)])

Comments

ASUN supports block comments:

/* user list */
[{id@int, name@str}]:
  (1, Alice),
  (2, Bob)

Line comments are not part of the format.

Whitespace

• whitespace between structural tokens is ignored
• unquoted strings are trimmed at the outer edges
• pretty multi-line layout is recommended but not required