2 files changed, 112 insertions, 0 deletions
diff --git a/src/dune b/src/dune
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--- /dev/null
+++ b/src/dune
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+(executable
+ (name main))
+\ No newline at end of file
diff --git a/src/main.ml b/src/main.ml
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--- /dev/null
+++ b/src/main.ml
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+exception IntegerOverflow of unit
+
+(** Signature for a module describing an identifier.
+    
+    We often need identifiers (for definitions, variables, etc.) and in
+    order to make sure we don't mix them, we use a generative functor
+    (see [IdGen]).
+*)
+module type Id = sig
+  type id
+
+  type 'a vector
+
+  val zero : id
+
+  val incr : id -> id
+
+  val to_string : id -> string
+end
+
+(** Generative functor for identifiers.
+
+    See [Id].
+*)
+module IdGen () : Id = struct
+  type id = int
+
+  type 'a vector = 'a list (* TODO: use a map *)
+
+  let zero = 0
+
+  let incr x =
+    (* Identifiers should never overflow (because max_int is a really big
+     * value - but we really want to make sure we detect overflows if
+     * they happen *)
+    if x == max_int then raise (IntegerOverflow ()) else x + 1
+
+  let to_string = string_of_int
+end
+
+type name = string list
+(** A name such as: `std::collections::vector` *)
+
+module TypeVarId = IdGen ()
+
+module TypeDefId = IdGen ()
+
+module VariantId = IdGen ()
+
+module FieldId = IdGen ()
+
+module RegionVarId = IdGen ()
+
+type type_var = {
+  index : TypeVarId.id;  (** Unique index identifying the variable *)
+  name : string;  (** Variable name *)
+}
+
+type region_var = {
+  index : RegionVarId.id;  (** Unique index identifying the region *)
+  name : string option;  (** Region name *)
+}
+
+(** A region.
+    
+    Regions are used in function signatures (in which case we use region variable
+    ids) and in symbolic variables and projections (in which case we use region
+    ids).
+ *)
+type 'rid region =
+  | Static  (** Static region *)
+  | Var of 'rid  (** Non-static region *)
+
+(** The type of erased regions.
+    
+    We could use unit, but having a dedicated type makes things more explicit.
+ *)
+type erased_region = Erased
+
+(* TODO *)
+type rty = unit
+
+type field = { name : string; ty : rty }
+
+type variant = { name : string; fields : field FieldId.vector }
+
+type type_def_kind =
+  | Struct of field FieldId.vector
+  | Enum of variant VariantId.vector
+
+type type_def = {
+  def_id : TypeDefId.id;
+  name : name;
+  region_params : region_var RegionVarId.vector;
+  type_params : type_var TypeVarId.vector;
+  kind : type_def_kind;
+}
+
+module Id0 = IdGen ()
+
+module Id1 = IdGen ()
+
+let x0 = Id0.zero
+
+let x1 = Id0.incr x0
+
+let () =
+  let _ = print_endline "Hello, world!" in
+  let _ = print_endline (Id0.to_string x1) in
+  ()