package ocaml-base-compiler

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in-package search v0.2.0

Package contains no libraries

Unification traces are used to explain unification errors when printing error messages

type position =

| First
| Second

type desc = {

t : Types.type_expr;
expanded : Types.type_expr option;

}

type 'a diff = {

got : 'a;
expected : 'a;

}

type 'a escape =

| Constructor of Path.t
| Univ of Types.type_expr
(*
The type_expr argument of Univ is always a Tunivar _, we keep a type_expr to track renaming in Printtyp
*)
| Self
| Module_type of Path.t
| Equation of 'a

Scope escape related errors

Errors for polymorphic variants

type fixed_row_case =

| Cannot_be_closed
| Cannot_add_tags of string list

type variant =

| No_intersection
| No_tags of position * (Asttypes.label * Types.row_field) list
| Incompatible_types_for of string
| Fixed_row of position * fixed_row_case * Types.fixed_explanation
(*
Fixed row types, e.g. 'a. [> `X] as 'a
*)

type obj =

| Missing_field of position * string
| Abstract_row of position
| Self_cannot_be_closed

type 'a elt =

| Diff of 'a diff
| Variant of variant
| Obj of obj
| Escape of {
1. context : Types.type_expr option;
2. kind : 'a escape;
}
| Incompatible_fields of {
1. name : string;
2. diff : Types.type_expr diff;
}
| Rec_occur of Types.type_expr * Types.type_expr

type t = desc elt list

val diff : Types.type_expr -> Types.type_expr -> desc elt

val map_diff : ('a -> 'b) -> 'a diff -> 'b diff

map_diff f {expected;got} is {expected=f expected; got=f got}

val flatten : (Types.type_expr -> Types.type_expr -> 'a) -> t -> 'a elt list

flatten f trace flattens all elements of type desc in trace to either f x.t expanded if x.expanded=Some expanded or f x.t x.t otherwise

val swap : t -> t

Switch expected and got

val explain : 
  'a elt list ->
  (prev:'a elt option -> 'a elt -> 'b option) ->
  'b option

explain trace f calls f on trace elements starting from the end until f ~prev elt is Some _, returns that or None if the end of the trace is reached.