Merge #975: add context notes

Author: Anton-Latukha

src/Nix/Context.hs

@@ -9,6 +9,7 @@ import           Nix.Expr.Types.Annotated       ( SrcSpan
                                                 )
 import           Nix.Utils                      ( Has(..) )
 
+--  2021-07-18: NOTE: It should be Options -> Scopes -> Frames -> Source(span)
 data Context m t = Context
     { scopes  :: Scopes m t
     , source  :: SrcSpan

src/Nix/Convert.hs

@@ -204,6 +204,8 @@ instance ( Convertible e t f m
           (M.lookup "outPath" s)
       _ -> stub
 
+  --  2021-07-18: NOTE: There may be cases where conversion wrongly marks the content to have a context.
+  --  See: https://github.com/haskell-nix/hnix/pull/958#issuecomment-881949183 thread.
   fromValue = fromMayToValue $ TString HasContext
 
 instance Convertible e t f m

src/Nix/String.hs

@@ -46,6 +46,7 @@ import           Nix.Expr.Types                 ( VarName(..)
 
 -- ** Context
 
+--  2021-07-18: NOTE: it should be ContextFlavor -> Varname.
 -- | A Nix 'StringContext' ...
 data StringContext =
   StringContext
@@ -104,6 +105,7 @@ type WithStringContext = WithStringContextT Identity
 
 -- ** NixString
 
+--  2021-07-18: NOTE: It should be Context -> Contents.
 data NixString =
   NixString
     { nsContents :: !Text