Graphql-js: Better Flow type defs for field resolvers

[leebyron]

When writing resolvers for GraphQL types in a flow-typed environment, the Flow types should aid as much as possible.

• [x] Do not require casting through (: any) for typical behavior.
• [ ] Proper typing of context
• [ ] Proper typing of source
• [ ] Proper typing of return
• [ ] Proper typing of arguments

[leebyron]

This was originally inspired by discussion in #554.

[jamiehodge]

@leebyron is there any progress on this meta issue? It would really helpful to get end-to-end typing of the graph and the possibility of leveraging that in the client.

[jamiehodge]

@leebyron are you still working on this issue? Is there something I or others could help with?

[corydeppen]

Has there been any additional consideration for what it will take to move forward with the remainder of the typings for resolvers?

[sibelius]

@gtkatakura is using conditional mapped types to improve types: https://github.com/gtkatakura/fullstack-challenge/commit/36cc1050768e29824f7c7114d22c131d43aefef9

[gtkatakura-bysoft]

If it helps... proper typing of return (only for GraphQLScalarType) in TypeScript

https://github.com/gtkatakura/fullstack-challenge/commit/bc01861cb7f34fd5bc65b892ef9b33aedadab3e6

[sibelius]

typing for GraphQLScalarType https://github.com/graphql/graphql-js/pull/1522