refactor stack vm to use a basic block ish structure

src/Gyehoek/Scheme/Syntax.hs

@@ -142,7 +142,9 @@ makeBaseFunctor ''Exp
 
 
 instance DatumIso Name where
-  datumIso = S.symbol >>> S.iso MkName (review _Unwrapped')
+  datumIso = S.decorate S.SynVariable
+    >>> S.symbol
+    >>> S.iso coerce coerce
 
 primDatumIso
   :: (Text -> Text)