Richer import syntax

[dfreeman]

This PR (built on top of the diff for #8) introduces support for graphql-import-style import directives, as outlined in #3. While there's still no official spec for modularizing GraphQL schemas and operations across files, the graphql-import package gets over half a million downloads a week, so seems like the likeliest thing we should attempt syntactic compatibility with for the time being.

A couple thoughts/questions:

• Should we explicitly deprecate the old syntax? Like-for-like migration should be pretty straightforward: find/replace #import ➡️ # import * from in all .graphql files in a given codebase.
• This doesn't support renaming identifiers as described in Fragment can't be imported more than once #1 (and graphql-import doesn't support that at all), but it at least opens the door to it if that's something folks decide is worth investing in down the line. I think I was misremembering the heart of that issue. The way this actually stands, if you want to import and use Foo, and it references Bar, you'd have to # import Foo, Bar from ... in order for that to work. That does solve Fragment can't be imported more than once #1, but is probably more painful in the general case—maybe that's just when you fall back to import * 🤔

[csantero]

@dfreeman Yeah, let's deprecate. Could you print a message that includes the name of the file that the legacy import occurs in, as well a blurb to the readme with migration instructions?

[csantero]

@dfreeman I just tried this PR in my own app and it works great, before and after migrating syntax with the global search-and-replace. import * is fine for my own use-case, since all my files have exactly one top-level query or fragment.

[dfreeman]

@csantero Glad to hear it! My main motivator for this update was wanting to be able to tell syntactically which fragments come from which imports for TypeScript reasons, but I imagine for many folks # import * will be just fine.

I added a deprecation message that links to a new blurb in the README about migration, so hopefully this should be good to go now 🙂

[csantero]

This is great, thanks!

[csantero]

Released as 0.4.1