Targets · JSON · Object format

Object format

Every canonical node in the object form, keyword by keyword — the exact JSON that the Structure types serialise to. Field types and shared nodes link back to their definition on the Structure page.

JSON is the canonical command form every module is stored in — the interchange the other targets render from, not a language you run. These pages describe that form.

Introduction — what the JSON form is, and how to read the rest of this section.
Capabilities — which high-level features are possible — deferred to whichever target this JSON renders to.
Example — a full program using every keyword, in the canonical JSON form.
Naming considerations — how Program's dotted names are stored, verbatim and un-munged.
Object format — every node in the self-describing object form, keyword by keyword.
Array format — every node in the compact tagged-array form, keyword by keyword.
Project setup — there is no build; how a module file is stored, read and rendered onward.
Reserved words — why the canonical form has none, and never escapes a name.

Conventions

How each shape maps into object form, node by node:

Case	Object based	Array based
A keyword node	an object under its keyword, `{ "MODULE": { … } }`	a tagged array, `["MODULE", …]`
A union value (one option chosen from several)	a single-key object `{ "<option>": value }`	a two-element array `["<option>", value]`
An optional value that is absent	the field is `null`	the position is `null`
An optional value at the end of an array	the key is omitted	the trailing position is dropped entirely
A union option carrying no data (e.g. a direction)	the bare option name, `"binding"`	the bare option name, `"binding"`
An identifier (a declared name)	the bare name string, `"Greet"`	the bare name string, `"Greet"`

ROOT

{ "ROOT": {
  "modules": [
    { "MODULE": { "name": "App", "modules": [], "types": [], "functions": [], "constants": [], "natives": [], "nativeTypes": [] } }
  ],
  "natives": [
    { "NATIVE": { "platform": "js", "code": "globalThis.__boot = true;" } }
  ],
  "run": [
    { "CALL": { "functionName": "App.Main", "typeArguments": [], "arguments": [] } }
  ]
} }

ROOT keyword JSON object definition

Field	Type	Description
`modules`	array of MODULE	The top-level modules.
`natives`	array of NATIVE	Per-target native setup blocks that run as the program starts.
`run`	array of BodyCommand	The run body: the program's entry point, where a bare CALL may appear.

MODULE

{ "MODULE": {
  "name": "App",
  "modules": [],
  "types": [
    { "TYPE": { "name": "Profile", "genericTypes": [], "fields": [
      { "FIELD": { "name": "name", "type": "Text" } }
    ], "options": [], "natives": [] } }
  ],
  "functions": [
    { "FUNCTION": { "name": "Greet", "genericTypes": [], "inputs": [
      { "INPUT": { "name": "name", "type": "Text", "direction": "forward" } }
    ], "holes": [], "return": { "name": "__return", "type": "Text", "optionalDirection": null },
      "body": { "implementations": [
        { "NATIVE": { "platform": "js", "code": "return 'Hi ' + name;" } }
      ] } } }
  ],
  "constants": [
    { "LET": { "name": "MaxRetries", "type": "Maths.Integer", "value": { "constant": { "literal": { "integer": 3 } } } } }
  ],
  "natives": [],
  "nativeTypes": []
} }

MODULE keyword JSON object definition

Field	Type	Description
`name`	Identifier	The module's name.
`modules`	array of MODULE	Nested modules.
`types`	array of TYPE	The module's types.
`functions`	array of FUNCTION	Derived functions.
`constants`	array of LET	Module-level constants, each a `LET` binding a constant expression.
`natives`	array of FUNCTION	Native functions (body is `implementations`).
`nativeTypes`	array of native type	Native type declarations.

FUNCTION

{ "FUNCTION": {
  "name": "Welcome",
  "genericTypes": [],
  "inputs": [
    { "INPUT": { "name": "profile", "type": "App.Profile", "direction": "binding" } }
  ],
  "holes": [
    { "HOLE": { "name": "row", "type": "Text", "inputs": [
      { "INPUT": { "name": "line", "type": "Text", "direction": "forward" } }
    ] } }
  ],
  "return": { "name": "__return", "type": "Text", "optionalDirection": null },
  "body": { "body": [
    { "LET": { "name": "label", "type": "Text", "value": { "reference": "profile" } } }
  ] }
} }

FUNCTION keyword JSON object definition

Field	Type	Description
`name`	Identifier	The function's name.
`genericTypes`	array of Reference	Names of the generic type parameters, if any.
`inputs`	array of INPUT	The typed parameters.
`holes`	array of HOLE	The callback parameters the caller fills. Empty for most functions.
`return`	Return or null	The return name and type, or null for no return.
`body`	FunctionBody union	`{ "body": […] }` for a derived function, or `{ "implementations": […] }` for a native one.

INPUT

{ "INPUT": { "name": "profile", "type": "App.Profile", "direction": "binding" } }

INPUT keyword JSON object definition

Field	Type	Description
`name`	Identifier	The parameter name.
`type`	Text	The parameter's type, as a name.
`direction`	Direction	One of `"forward"`, `"binding"`, `"reverse"`.
`default`	ConstantExpression, optional	The default value; the key is absent when there is none.

HOLE

{ "HOLE": { "name": "row", "type": "Text", "inputs": [
  { "INPUT": { "name": "line", "type": "Text", "direction": "forward" } }
] } }

HOLE keyword JSON object definition

Field	Type	Description
`name`	Identifier	The hole's name.
`type`	Text or null	The block's return type, or null if it returns nothing.
`inputs`	array of INPUT	The values passed into the block.

NATIVE

{ "NATIVE": { "platform": "js", "code": "return 'Hi ' + name;" } }

NATIVE keyword JSON object definition

Field	Type	Description
`platform`	Text	The target name: `dart`, `swift`, `js`, `nodejs`, `ts`, `go`, `rust`, `zig`, `glsl` or `php`.
`code`	Text	The host source for that target — a function body, or a type alias for a native type.

TYPE

{ "TYPE": {
  "name": "Status",
  "genericTypes": [],
  "fields": [],
  "options": [
    { "OPTION": { "name": "active", "type": "App.Profile" } },
    { "OPTION": { "name": "pending", "type": "Text" } }
  ],
  "natives": []
} }

TYPE keyword JSON object definition

Field	Type	Description
`name`	Identifier	The type's name.
`genericTypes`	array of Reference	Generic type parameter names, if any.
`fields`	array of FIELD	The record's fields; empty for a union or native type.
`options`	array of OPTION	The union's options; empty for a record or native type.
`natives`	array of NATIVE	Per-target native implementations; empty for a record or union.

FIELD

{ "FIELD": { "name": "age", "type": "Maths.Integer" } }

FIELD keyword JSON object definition

Field	Type	Description
`name`	Identifier	The field name.
`type`	Text	The field's type, as a name.
`default`	ConstantExpression, optional	The field's default; the key is absent when there is none.

OPTION

{ "OPTION": { "name": "active", "type": "App.Profile" } }

OPTION keyword JSON object definition

Field	Type	Description
`name`	Identifier	The option name; reads back as an Optional of its type.
`type`	Text	The option's payload type.

LET

{ "LET": {
  "name": "label",
  "type": "Text",
  "value": { "call": {
    "functionName": "Maths.Integer.ToString",
    "typeArguments": [],
    "arguments": [ { "reference": "count" } ]
  } }
} }

LET keyword JSON object definition

Field	Type	Description
`name`	Identifier	The bound name.
`type`	Text	The value's type.
`value`	AssignmentValue union	`{ "reference": name }` or `{ "call": FunctionCall }`.

STATE

{ "STATE": { "name": "count", "type": "Maths.Integer", "initial": { "constant": { "literal": { "integer": 0 } } }, "lockable": false } }

STATE keyword JSON object definition

Field	Type	Description
`name`	Identifier	The cell's name.
`type`	Text	The cell's type.
`initial`	AssignmentValue or null	The starting value (reference, call or constant), or null for a locked-empty cell.
`lockable`	Logic.Maybe	`true` for a `LOCKED` cell, otherwise `false`.

REVERSE

{ "REVERSE": {
  "name": "submit",
  "type": "App.Profile",
  "body": [
    { "LET": { "name": "response", "type": "Network.Web.Response",
      "value": { "call": {
        "functionName": "Network.Web.Client.Post", "typeArguments": [],
        "arguments": [ { "reference": "profile" } ] } } } }
  ],
  "setters": [
    { "SET": { "outerSettable": "saved", "innerValue": "response" } }
  ]
} }

REVERSE keyword JSON object definition

Field	Type	Description
`name`	Identifier	The reverse's name.
`type`	Text	The type being written back.
`body`	array of BodyCommand	The work done before the write.
`setters`	array of SET	The write-backs into outer state.

SET

{ "SET": { "outerSettable": "saved", "innerValue": "response" } }

SET keyword JSON object definition

Field	Type	Description
`outerSettable`	Text	The outer state cell to write into.
`innerValue`	Text	The name of the inner value to write.

WITH

{ "WITH": {
  "module": "Network.Web.Client",
  "replacement": "Network.Web.Mock",
  "body": [
    { "LET": { "name": "response", "type": "Network.Web.Response",
      "value": { "call": {
        "functionName": "Network.Web.Client.Post", "typeArguments": [],
        "arguments": [ { "reference": "profile" } ] } } } }
  ]
} }

WITH keyword JSON object definition

Field	Type	Description
`module`	Text	The module whose implementation is swapped.
`replacement`	Text	The module swapped in for the block.
`body`	array of BodyCommand	The commands the swap applies over.