AS far as I know, there is no GraphQL library for Nim.
If you're ever wondering if a Nim package exists, a good place to look is the Nimble package list here: https://github.com/nim-lang/packages/blob/master/packages.json.
Alternatively, you can always use Nimble's built in search feature: https://github.com/nim-lang/nimble#nimble-search
A GRaphQL library for Nim would be pretty cool as Nim is generally lacking in any Database abstraction layers. There are no well maintained Nim ORMs or ODMs to my knowledge outside of maybe Nimongo for MongoDb. Nim does, however, ship with built in SQL drivers.
If you wanted to implement a GraphQL package for Nim, I would recommend starting by reading the documentation for the parser written in C++ here: https://github.com/graphql/libgraphqlparser
Then, I would read the GraphQL spec here: http://facebook.github.io/graphql/October2016/#
Then, I would take a look a look at the Python GRaphQL library, Graphene, here: https://github.com/graphql-python/graphene
I feel like it would be simple enough to essentially "copy" Graphene as Python and Nim share very similar syntax.
Regarding libGraphQlParser
The c++ code doesn't wrap code in namespaces, and has very simple high-level calls using standard types, so it should work well with c2nim converting c or cpp code (untested of course ;-) )
In other words, a great project in which to learn to use c2nim.
EDIT: it is a BSD licence (whatever the implications are for that)
I just created nimgraphql using nimgen. Curious if it meets the community's need.
Feedback is greatly appreciated.
now we have a graphql implementation in Nim https://github.com/status-im/nim-graphql.
it works with query and mutation part of graphql, have a nice API for custom scalar and simple resolver interface.
shipped with a http server, a playground http server, and a http client.
features that is still missing are: