Documentation

Object field separation operator.

Use this to provide handlers for fields of an object.

Say you had the following GraphQL type with "foo" and "bar" fields, e.g.

  type MyObject {
    foo: Int!
    bar: String!
  }

You could provide handlers for it like this:

>>> :m +System.Environment
>>> let fooHandler = pure 42
>>> let barHandler = System.Environment.getProgName
>>> let myObjectHandler = pure $ fooHandler :<> barHandler :<> ()

Specify a default value for a type in a GraphQL schema.

GraphQL schema can have default values in certain places. For example, arguments to fields can have default values. Because we cannot lift arbitrary values to the type level, we need some way of getting at those values. This typeclass provides the means.

To specify a default, implement this typeclass.

The default implementation is to say that there *is* no default for this type.

Translate a Handler into a DynamicUnionValue type required by Union handlers. This is dynamic, but nevertheless type-safe because we can only tag with types that are part of the union.

Use e.g. like "unionValue @Cat" if you have an object like this:

>>> type Cat = API.Object "Cat" '[] '[API.Field "name" Text]

and then use `unionValue @Cat (pure (pure Felix))`. See `examples/UnionExample.hs` for more code.