Cannot merge typed functions with simple type system

[Glen Whitney]

Consider

typed.types = [
  { name: 'number',    test: x => typeof x === 'number' },
  { name: 'string',    test: x => typeof x === 'string' }
]

const vanilla = typed({number: n => n+2})
console.log('Vanilla', vanilla(2))

const sprinkles = typed(vanilla, {string: s => s + ' two'})
console.log('With sprinkles', sprinkles('cookie'), sprinkles(3))

Looks perfectly innocuous, yet it fails with TypeError: Unknown type "Object".
Somehow, the infrastructure should not crumble because the the client just wants a few types...

[Jos de Jong]

I think you want to merge two typed functions, however, in following line:

const sprinkles = typed(vanilla, {string: s => s + ' two'})

the second argument is no typed-function but a plain Object. I guess it will work if you do

const sprinkles = typed(vanilla, typed({string: s => s + ' two'}))

If that works please let me know, I would like a cookie with sprinkles too 😋 .

It would be nice though if we could make the error message more informative at least, or extend the API to support this too.

[Glen Whitney]

Ah, right. Taking Object out of the type system simply makes it so that typed-function can't generate the proper error message (I didn't realize my syntax never worked so far, although I don't see any reason why it shouldn't). So this isn't as big a problem, but it is still a problem. I will file a PR so that typed-function doesn't depend on the type system to generate this error message.