default constructors

[alex-s168]

would be useful for writing generic code.

I don't know how zero Maybe<x> = None works, but that could somehow be used for this

[andrew-johnson-4]

I think this could be a feature with default arguments to functions.

In the compiler right now there is a "default" constructor for one of the AST cases.

type AST = ASTEOF
         | ASTNil
         | App { is-cons: U64, left: AST[], right: AST[] }
         | Var { key: CString, token: Token }
         | Lit { key: CString, token: Token }
         | Abs { lhs: AST[], rhs: AST[], tt: Type }
         | AType { tt: Type }
         | Seq { left: AST[], right: AST[] }
         | Glb { key: Token , val: AST[] }
         | Typedef { lhs: AST[] , rhs: AST[] }
         | Meta { description: AST[] };

let $"App"(left: AST[], right: AST[]): AST = App { false, left, right };

default arguments could make this easier to declare.