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diff --git a/src/Data/GraphQL/Execute.hs b/src/Data/GraphQL/Execute.hs
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+{-# LANGUAGE OverloadedStrings #-}
+-- | This module provides the function to execute a @GraphQL@ request --
+--   according to a 'Schema'.
+module Data.GraphQL.Execute (execute) where
+
+import Control.Monad (MonadPlus(..))
+import Data.GraphQL.Error
+import qualified Data.List.NonEmpty as NE
+import Data.List.NonEmpty (NonEmpty((:|)))
+import qualified Data.Aeson as Aeson
+import qualified Data.GraphQL.AST as AST
+import qualified Data.GraphQL.AST.Core as AST.Core
+import qualified Data.GraphQL.AST.Transform as Transform
+import Data.GraphQL.Schema (Schema)
+import qualified Data.GraphQL.Schema as Schema
+
+-- | Takes a 'Schema', a variable substitution function ('Schema.Subs'), and a
+--   @GraphQL@ 'document'. The substitution is applied to the document using
+--  'rootFields', and the 'Schema''s resolvers are applied to the resulting fields.
+--
+--   Returns the result of the query against the 'Schema' wrapped in a /data/ field, or
+--   errors wrapped in an /errors/ field.
+execute
+  :: (MonadPlus m)
+  => Schema m -> Schema.Subs -> AST.Document -> m Aeson.Value
+execute schema subs doc = do
+    coreDocument <- maybe mzero pure (Transform.document subs doc)
+    document schema coreDocument
+
+document :: MonadPlus m => Schema m -> AST.Core.Document -> m Aeson.Value
+document schema (op :| []) = operation schema op
+document _ _ = error "Multiple operations not supported yet"
+
+operation :: MonadPlus m => Schema m -> AST.Core.Operation -> m Aeson.Value
+operation schema (AST.Core.Query flds)
+    = runCollectErrs (Schema.resolve (NE.toList schema) (NE.toList flds))
+operation schema (AST.Core.Mutation flds)
+    = runCollectErrs (Schema.resolve (NE.toList schema) (NE.toList flds))