Use computation expressions for defining schema

We talked with @johnberzy-bazinga about idea of using cexprs for defining schemas, i.e instead of current:

let Person = Define.Object("Person", "description", [
    Define.Field("firstName", String, "Person's first name", fun ctx p -> p.FirstName)
    Define.Field("lastName", String, "Person's last name", fun ctx p -> p.LastName)
])

have something like:

let Person = outputObject "Person" {
    description "description"
    field "firstName" String "Person's first name" [] (fun _ p -> p.FirstName)
    field "lastName" String "Person's last name" [] (fun _ p -> p.LastName)
}

This topic is to discuss about that. Is it even possible? Is it feasible?

[Horusiath]

@Lenne231 there are several issues with following graphql-js desing:

1. You’re basically defining schema twice (first time as string, second as object with resolver methods). While this may be solution for javascript - because there’s no way to annotate GraphQL type system there - it looks counterproductive in typed languages.
2. Since it’s a string-based definition, you loose all of the power given you by the IDE. No syntax highlighting, no autocompletion. Even trivial things, like checking if you correctly closed all opened scopes and there’s no brace missing, must be done by you. Type provider may validate that string, but it won’t show you where in your string the bug is hidden.
3. In case of typos in type names or identifiers, there’s no way to guarantee that Type Provider will behave correctly. In optimistic case it won’t compile, as under the typo it will find, that GraphQL schema is not total, and there are some not-described types. But again no help from the complier or IDE side there. In pessimistic case it will swallow that, and throw an error at runtime, when you’ll try to call misspelled field.

[Swoorup]

Have to add that consuming the API in this form: https://github.com/GT-CHaRM/CHaRM.Backend/blob/master/src/CHaRM.Backend/Schema/Item.fs

makes it much more simpler and easier to implement than the current form.