Minor improvement in error reporting.

Use simple name "int", "string" etc instead of
internal representation.

src/compiler/flx_core/flx_btype.ml

@@ -290,7 +290,12 @@ and str_of_btype typ =
   | BTYP_sum ts -> "BTYP_sum(" ^ ss ts ^")"
   | BTYP_compactsum ts -> "BTYP_compactsum(" ^ ss ts ^")"
   | BTYP_unitsum n -> string_of_int n
-  | BTYP_inst (it, i,ts,mt) -> "BTYP_inst("^str_of_instkind it ^","^string_of_int i^"["^ss ts^"]:"^Flx_kind.sk mt^")"
+  | BTYP_inst (it, i,ts,mt) -> 
+    begin match Flx_concordance.get_type_name i with
+    | Some name -> name
+    | None ->  
+     "BTYP_inst("^str_of_instkind it ^","^string_of_int i^"["^ss ts^"]:"^Flx_kind.sk mt^")"
+    end
   | BTYP_finst (i,ks,dom,cod) -> "BTYP_finst("^string_of_int i^"["^sks ks^"]:"^sk dom^"->"^sk cod^")"
   | BTYP_vinst (i,ts,mt) -> "BTYP_vinst("^string_of_int i^"["^ss ts^"]:"^Flx_kind.sk mt^")"
   | BTYP_tuple ts -> "BTYP_tuple(" ^ ss ts ^ ")"

src/compiler/flx_core/flx_print.ml

@@ -742,7 +742,11 @@ and sb bsym_table depth fixlist counter prec tc =
       ">"
 
     | BTYP_inst (it,i,ts,mt) ->
-      0, (match bsym_table with 
+      0, (
+        match Flx_concordance.get_type_name i with
+        | Some name -> name
+        | None ->
+        match bsym_table with 
         | Some tab -> let name = qualified_name_of_bindex tab i in
           (* print_endline ("DEBUG: flx_print: BTYP_inst " ^ si i ^ ": " ^ name);  *)
           str_of_instkind it ^ " " ^ name

src/packages/concordance.fdoc

@@ -114,5 +114,12 @@ let flx_decr_int = 203
 let flx_land = 210
 let flx_lor = 211
 let flx_lnot = 212
+
+let get_type_name (x:int) : string option =
+match x with 
+| 102 -> Some "int"
+| 112 -> Some "size"
+| 402 -> Some "string"
+| _ -> None
 @
 

src/packages/strings.fdoc

@@ -22,7 +22,7 @@ This type is deprecated, to be repalced by C++11 unicode string type.
 @tangle string.flx
 typedef cstring = +char;
 type string = "::std::basic_string<char>" 
-  requires Cxx_headers::string,
+  requires index TYPE_string, Cxx_headers::string,
   header '#include "flx_serialisers.hpp"',
   encoder "::flx::gc::generic::string_encoder",
   decoder "::flx::gc::generic::string_decoder"