Keywords

Keywords are case-sensitive. If an identifier spellings match a keyword, it is read as that keyword, not as a user name.

Keyword list

Spelling	Role
`is`	Used in type and pattern positions where grammatically allowed
`void`	Void type / literal contexts
`switch`	Not supported in current Spine (reserved; may error if used)
`match`	Match expressions
`if`	Conditionals
`else`	Branches
`default`	Not supported in current Spine (reserved)
`throw`	Not supported in current Spine (reserved)
`as`	Cast: `expr as Type`
`Struct`	Struct declarations; also allowed as some enum variant names
`Annotation`	Annotation declarations and variant names
`Enum`	Enum declarations and variant names
`namespace`	Namespace blocks
`import`	Imports
`return`	Return from function or closure
`fail`	Explicit failure with strategy
`break`	Exit loop (optional value)
`continue`	Continue loop
`stream`	Used in stream-related grammar
`const`	Constant inside function/closure body
`let`	Binding inside function/closure body
`for`	Loops
`while` / `do`	Loops
`in`	`for x in iterable`
`function`	Top-level function

true and false are boolean literals and cannot be used as ordinary identifiers.

These behave like ordinary identifiers except in declaration headings:

Singleton in Singleton Name : Type = value
Ingest, Outlet, KeyValueApi, etc. as the leading type in Type Name { ... } wired declarations

Elsewhere, Ingest and similar spellings are normal names.

@ after a name attaches a version (Thing@1). A lone @ starts an annotation on a field.