Simplify import evaluation.

src/Data/Syntax/Declaration.hs

@@ -217,26 +217,8 @@ instance Eq1 Import where liftEq = genericLiftEq
 instance Ord1 Import where liftCompare = genericLiftCompare
 instance Show1 Import where liftShowsPrec = genericLiftShowsPrec
 
--- instance ( Show l
---          , Show t
---          , Members (Evaluating (Value l t)) es
---          , Evaluatable t (Value l t) (Base t)
---          , Recursive t
---          , FreeVariables t
---          )
---          => Evaluatable t (Value l t) Import where
---   eval (Import from _ _) = do
---     interface <- require @(Value l t) @t (subterm from)
---     -- TODO: Consider returning the value instead of the interface.
---     Interface _ env <- maybe
---                            (fail ("expected an interface, but got: " <> show interface))
---                            pure
---                            (prj interface :: Maybe (Value.Interface l t))
---
---     modify (envUnion env)
---     pure interface
---
-instance Evaluatable Import
+instance Evaluatable Import where
+  eval (Import from _ _) = require (subterm from) >> pure unit
 
 
 -- | An imported symbol