Idris-graphql

An Idris client for GraphQL.

For example the GraphQL schema:

type Query {
  Movie: Movie
}

type Movie {
  releaseDate: String
  actors: [!Actor]
}

type Actor {
  name: !String
}

Corresponds to a value Movies : Schema ["Query", "Movie", "Actor"]. We can then build queries for that schema:

inception : Query Movies
inception = Qu
  [ "inception" ::: fieldA "Movie" [("title", "Inception")]
     (Qu [ field "releaseDate" TrivScalar
         , field "actors" $
             Qu [ field "name" TrivScalar]
         ])
  ]

Which corresponds to the GraphQL query:

Movie(title: "Inception") {
  releaseDate
  actors {
    name
  }
}

A query of type Query Movies is guaranteed to be a valid query for the schema Movies.

The request : (url : String) -> (q : Query sch) -> JS_IO (Either String (Value.responseType q)) function results in either a network error, or a value whose type depends on the input query. For example, request inception will (if there is no network error), produce a value of type:

Maybe (Record [("Movie",
                Maybe (Record [("releaseDate", Maybe String),
                               ("actors", Maybe (List (Record [("name", String)])))]))]) : Type

Goals

• A type of valid GraphQL schema definitions.
• A type of valid GraphQL queries which depends on the type of schema.
• Format queries for sending to APIs.
• Type provider which reads a schema value from an SDL (Schema Defintion Language) text-file.
• Type provider which uses API reflection for querying an API for it's schema.
• A request function whose return type depends on the schema of input query. The return type should use extensible records.

TODO

• Arguments in queries are completely ignored for the moment (with respect to the schema).
• Add more schema top-level types.
• Add implementation using idris-http when targetting C (only node target is currently supported).

Build

(Have idris and npm installed.)

npm install
idris --codegen node --build idris-graphql.ipkg