Claro/docs/ADVANCED_STATIC_TYPING.md

Advanced Static Typing

Claro v1.18.26 adds the first advanced static-typing foundation: typed containers checked by claro typecheck.

Typed lists

SET names AS LIST OF TEXT TO LIST
ADD "Ada" TO names
ADD "Grace" TO names

The type checker now rejects wrong item types:

SET names AS LIST OF TEXT TO LIST
ADD 123 TO names

Output:

Type mismatch for list names: expected TEXT item, but this value looks like NUMBER.

Typed maps

SET scores AS MAP OF NUMBER TO MAP
PUT scores KEY "math" VALUE 98

The type checker rejects wrong value types:

SET scores AS MAP OF NUMBER TO MAP
PUT scores KEY "oops" VALUE "high"

Output:

Type mismatch for map scores: expected NUMBER value, but this value looks like TEXT.

Status

This is currently a static checker feature. It improves claro typecheck and validation confidence. Runtime enforcement for every container mutation can be added later after the syntax is classroom-tested.