Module scalars 

The five type names the compiler knows as scalars, and the one it knows beside them.

Int, Float, Bool, Char and String are scalar: each is declared in Zelkova like any other type, and the compiler additionally knows the representation each target gives it. Scalar types is the rule; this module is the list it names.

A scalar is known by the qualified name of its declaration — package, module and name — and never by its spelling (DEC-15 decision 1). A module declaring its own Int declares an ordinary type that shares three letters with a scalar, and every phase treats it as one — which is why Scalar::declares takes a QualName and there is no entry point taking a bare Name. The same goes for a whole package: a dependency’s own Basics declaring type Int = Int declares Basics.Int of that package, and the five scalars are declared in zelkova-core only.

Why the list lives here and not in the typer

The typer is the only reader today: typer::canonical_type_to_typer_type maps four of the five onto its own literal types, and BOOL names the union an if condition is checked against. The list is nonetheless a fact about the language rather than about type inference, and the same five names answer questions the typer never asks — which names a module underneath Basics receives without an import, and which declarations may name nothing but themselves. It sits beside the phases for the same reason default_imports does.

Structs

Scalar

One scalar type: the module of zelkova-core its declaration lives in, and the name that declaration writes.

Constants

BOOL

Basics.Bool, which is a scalar and an ordinary union at once: the compiler knows its representation and nothing about its structure, so True and False stay constructors like any others.

CHAR

Char.Char.

FLOAT

Basics.Float.

INT

Basics.Int.

OPAQUE_SCALARS

The four scalars whose declaration is opaque (DEC-15 decision 2): nothing in the language constructs or inspects a value of one, so each declares only its own name and contributes no constructor.

POSITION

Basics.Position: the type a derivation hands differed and atConstructor for a constructor’s place in its declaration.

SCALARS

The five scalar types, in the order Scalar types lists them.

STRING

String.String.

Functions

opaque_scalar_of

The opaque scalar name declares, if it declares one — None for BOOL even though scalar_of would answer it, since BOOL is not in OPAQUE_SCALARS.

scalar_of

The scalar name declares, if it declares one.