Design type system

[DylanSp]

Type System Design

Base Types

Description	Name in Faust	Notes
Booleans	bool
Integers	int64	Implement with JS BigInt in interpreter
Double-precision floating-point	fp64	Implement with JS Number in interpreter
Strings	str	Required to be ASCII, but treated as an opaque type - Faust doesn't have a char type. See notes in roadmap
Void/Unit type	void	Return type for functions that don't return a value

Other Types

• Structs
• Tuples (probably implement up through 4-tuples; hold off on anything further)
• Enums (sum types) - individual variants can be empty, have anonymous fields, or be structs. (See https://github.com/DylanSp/faust-lang/issues/15)
• Fixed-length arrays (always bound-checked)

Generics

Structs, tuples, enums, and arrays can all be generic, taking some number of type parameters.

Notable omissions

• Any sort of null/undefined

[DylanSp]

Omissions for Stage 1

Not included now, but will probably be implemented later.

• Struct methods (just have plain functions)
• Interfaces/traits
• Higher-order functions (avoiding these simplifies compiler implementation)

[DylanSp]

Open question: should I expose fixed-length arrays to Faust users? Would it be possible to only expose an equivalent to C++'s std::vector<T> to users, and have fixed-length arrays only be allowed within the implementation of that type?