+(* src carr, tgt carr, uri, saturations, coerced position
+ * invariant:
+ * if the constant pointed by uri has n argments
+ * n = coerced position + saturations + FunClass arity
+ *)
+
+type saturations = int
+type coerced_pos = int
+type coercion_entry =
+ coerc_carr * coerc_carr * UriManager.uri * saturations * coerced_pos
+val add_coercion: coercion_entry -> unit
+val remove_coercion: (coercion_entry -> bool) -> unit