SafePrimitive.ts

// assures T is a primitive type
type TPrimitive<T> =
    T extends number ? number :
    T extends string ? string :
    // object, array, etc . . .
    // else
    never

type Safe<TKind extends string, T> = {
    kind: TKind
    value: TPrimitive<T>
}

const Safe =
    <TKind extends string, T >
        (kind: TKind) =>
        (value: TPrimitive<T>) =>
            ({ kind, value })



// boler plate
type Peso =  ReturnType<typeof Peso>
type Largura =  ReturnType<typeof Largura>

// Glossary
const Largura =
    Safe<"Largura",number>("Largura")  

const Peso =
    Safe<"Peso",number>("Peso")

// Operations
const cargaTotal = 
    (a: Peso, b: Peso) => Peso(a.value + b.value)

const larguraMaxima =
    (a: Largura, b: Largura) => Largura(a.value + b.value)

const densidade =
    (a: Peso, b: Largura) => a.value + b.value

// test
const a = cargaTotal(Peso(20), Peso(30))
const b = larguraMaxima(Largura(20), Largura(30))
const c = densidade(a, b)
const d = cargaTotal(Peso(20), Largura(30))