Eval: demand(F->)

src/Nix/Eval.hs

@@ -82,7 +82,6 @@ type MonadNixEval v m
  = ( MonadEval v m
  , Scoped v m
  , MonadValue v m
- , MonadValueF v m
  , MonadFix m
  , ToValue Bool m v
  , ToValue [v] m v
@@ -118,7 +117,7 @@ eval (NSym var ) = do
  mres <- lookupVar var
  maybe
  (freeVariable var)
- (demandF (evaledSym var))
+ (evaledSym var <=< demand)
  mres
 
 eval (NConstant x ) = evalConstant x
@@ -178,7 +177,7 @@ evalWithAttrSet aset body = do
  -- computed once.
  scope <- currentScopes :: m (Scopes m v)
  s <- defer $ withScopes scope aset
- let s' = demandF (fmap fst . fromValue @(AttrSet v, AttrSet SourcePos)) s
+ let s' = (fmap fst . fromValue @(AttrSet v, AttrSet SourcePos)) =<< demand s
  pushWeakScope s' body
 
 attrSetAlter
@@ -199,7 +198,7 @@ attrSetAlter (k : ks) pos m p val =
  (\x ->
  do
  (st, sp) <- fromValue @(AttrSet v, AttrSet SourcePos) =<< x
- recurse (demandF pure <$> st) sp
+ recurse ((pure <=< demand) <$> st) sp
  )
  (M.lookup k m)
  )
@@ -270,7 +269,7 @@ evalBinds recursive binds = do
  finalValue >>= fromValue >>= \(o', p') ->
  -- jww (2018-05-09): What to do with the key position here?
  pure $ fmap
- (\(k, v) -> ([k], fromMaybe pos (M.lookup k p'), demandF pure v))
+ (\(k, v) -> ([k], fromMaybe pos (M.lookup k p'), pure =<< demand v))
  (M.toList o')
 
  go _ (NamedVar pathExpr finalValue pos) = do
@@ -315,7 +314,7 @@ evalBinds recursive binds = do
  ms
  maybe
  (attrMissing (key :| []) Nothing)
- (demandF pure)
+ (pure <=< demand)
  mv
  )
  )
@@ -350,8 +349,8 @@ evalSelect aset attr = do
  extract x path@(k :| ks) = fromValueMay x >>= \case
  Just (s :: AttrSet v, p :: AttrSet SourcePos)
  | Just t <- M.lookup k s -> case ks of
- [] -> pure $ pure $ demandF pure t
- y : ys -> demandF (extract ?? (y :| ys)) t
+ [] -> pure $ pure $ pure =<< demand t
+ y : ys -> (extract ?? (y :| ys)) =<< demand t
  | otherwise -> Left . (, path) <$> toValue (s, p)
  Nothing -> pure $ Left (x, path)