Revert "Does not work"

This reverts commit cbf565d4c0.

AST.mli

@@ -161,7 +161,8 @@ type ('a, 'type_expr_typecheck) gadt_if =
    sufficient.
  *)
 type 'x x_sig = 'x
-constraint 'x = 'type_annotation * 'type_expr_typecheck
+constraint 'x = < annot:               'type_annotation;
+                  type_expr_typecheck: 'bool1 >
 
 type 'x ast = {
   types      : 'x type_decl reg list;
@@ -220,7 +221,8 @@ and 'x type_expr =
 | Function of (('x type_expr list) * 'x type_expr, 'type_expr_typecheck) gadt_if
 | Mutable  of ('x type_expr,                       'type_expr_typecheck) gadt_if
 | Unit     of (unit,                               'type_expr_typecheck) gadt_if
-constraint 'x = ('type_annotation * 'type_expr_typecheck)
+constraint 'x = < type_expr_typecheck: 'type_expr_typecheck;
+                  .. >
 constraint 'x = 'x x_sig
 
 and 'x cartesian = ('x type_expr, times) nsepseq reg
@@ -503,9 +505,15 @@ constraint 'x = 'x x_sig
 
 (* Variations on the AST *)
 
-type parse_phase = (unit * tfalse)
+type parse_phase = <
+  annot:               unit;
+  type_expr_typecheck: tfalse;
+>
 
-type typecheck_phase = (parse_phase type_expr *  ttrue)
+type typecheck_phase = <
+  annot:               typecheck_phase type_expr;
+  type_expr_typecheck: ttrue;
+>
 
 type t = parse_phase ast
 

Typecheck2.ml

@@ -3,7 +3,10 @@ module SMap = Map.Make(String)
 open AST
 
 type i = parse_phase
-type typecheck_phase = (parse_phase type_expr *  tfalse)
+type typecheck_phase = <
+  annot:               typecheck_phase type_expr;
+  type_expr_typecheck: tfalse;
+>
 type o = typecheck_phase
 
 type te = o type_expr list SMap.t (* Type environment *)