+ -----------------------------------------------------------
+ -- Heterogeneous Metaprogramming extension
+
+ | HsHetMetBrak PostTcType (LHsExpr id) -- code type brackets
+ | HsHetMetEsc PostTcType PostTcType (LHsExpr id) -- code type escape
+ | HsHetMetCSP PostTcType (LHsExpr id) -- code type cross-stage persistence
+