eca3c2d8d4
This allows schema definitions with side-effects for any type with a Monadic/Alternative implementation like IO for example.
35 lines
1.2 KiB
Haskell
35 lines
1.2 KiB
Haskell
{-# LANGUAGE CPP #-}
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{-# LANGUAGE OverloadedLists #-}
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{-# LANGUAGE LambdaCase #-}
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module Data.GraphQL.Execute where
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#if !MIN_VERSION_base(4,8,0)
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import Control.Applicative (Applicative, (<$>), pure)
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#endif
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import Control.Applicative (Alternative, empty)
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import qualified Data.Aeson as Aeson
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import Data.GraphQL.AST
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import Data.GraphQL.Schema
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type Response = Aeson.Value
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execute :: (Alternative f, Monad f) => Schema f -> Document -> f Response
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execute (Schema resolv0) doc = go resolv0 =<< root doc
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where
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root :: Applicative f => Document -> f Selection
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root (Document [DefinitionOperation (Query (Node _ _ _ [sel]))]) = pure sel
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root _ = error "root: Not implemented yet"
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go :: (Alternative f, Monad f) => Resolver f -> Selection -> f Response
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go resolv (SelectionField (Field _ n _ _ sfs)) =
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resolv (InputField n) >>= \case
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(OutputScalar s) ->
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if null sfs
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then (\s' -> Aeson.Object [(n, Aeson.toJSON s')]) <$> s
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else empty
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(OutputResolver resolv') -> (\r-> Aeson.Object [(n, r)]) <$> go resolv' (head sfs)
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_ -> error "go case resolv: Not implemented yet"
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go _ _ = error "go: Not implemented yet"
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