Whether or not a mutable field is atomic

Describes a mutable field/element.

Returns true is the mutable_flag is mutable or atomic. Should be called if not interested in the payload of Mutable.

Returns true is the mutable_flag is atomic. Should be called if not interested in the payload of Mutable.

Given the parameter m0 on mutable, return the mode of future writes.

The mod-bounds of a jkind

Information tracked about an individual type within the with-bounds for a jkind

This is used in the Typedtree. It is distinct from arg_label because Position argument labels are discovered through typechecking.

See also documentation for row_more, which enumerates how these constructors arise.

abbrev_memo allows one to keep track of different expansions of a type alias. This is done for performance purposes.

For instance, when defining type 'a pair = 'a * 'a, when one refers to an 'a pair, it is just a shortcut for the 'a * 'a type. This expansion will be stored in the abbrev_memo of the corresponding Tconstr node.

In practice, abbrev_memo behaves like list of expansions with a mutable tail.

Note on marshalling: abbrev_memo must not appear in saved types. Btype, with cleanup_abbrev and memo, takes care of tracking and removing abbreviations.

A history of conditions placed on a jkind.

INVARIANT: at most one sort variable appears in this history. This is a natural consequence of producing this history by comparing jkinds.

The types within the with-bounds of a jkind

The "quality" of a jkind indicates whether we are able to learn more about the jkind later.

We can never learn more about a Best jkind to make it "lower" (according to Jkind.sub / Jkind.sub_jkind_l). A Not_best, jkind, however, might have more information provided about it later that makes it lower.

Note that only left jkinds can be Best (meaning we can never compare less than or equal to a left jkind!)

Access to marks. They are stored in the scope field.

Transient type_expr. Should only be used immediately after Transient_expr.repr

Operations on transient_expr

Create a type with a fresh id

Create a type with a fresh id and no scope

Comparisons for functors

row_more returns a type_expr with one of the following type_descs (also described with the return from row_fixed, which varies similarly):

* Tvar: This is a row variable; it would occur in e.g. val f : [> `A | `B] -> int. When/if we learn more about a polymorphic variant, this variable might get unified with one of the other type_descs listed here, or a Tvariant that represents a new set of constructors to add to the row.

During constraint checking (toward the end of checking a type declaration, in Typedecl.check_constraints_rec) we Ctype.rigidify a type to make it so that its unification variables will not unify. When a Tvar row variable is rigidified, its fixed_explanation will be Rigid.

* Tunivar: This is a universally quantified row variable; it would occur in e.g. type t = { f : 'a. ([> `A | `B ] as 'a) -> int }. A Tunivar has a fixed_explanation of Univar.

* Tconstr: There are two possible ways this can happen:

1. This is an abstract #row type created by a private row type, as in type t = private [> `A | `B]. In this case, the fixed_explanation will be Fixed_private.

2. This is a locally abstract type created by Ctype.reify, which happens when a row variable is free in the type of the scrutinee in a GADT pattern match. The fixed_explanation will be Reified. Note that any manifest of a reified row variable is actually ignored by row_repr; this causes some incompletness in type inference.

* Tnil: Used to denote a static polymorphic variant (with no > or <).

* Tof_kind: See Wrinkle BW2 in Note With-bounds for GADTs in Jkind. Briefly, Tof_kind can appear as a row_more when computing the kind of a GADT with an existentially-bound row variable. The fixed_explanation will be Fixed_existential.

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It is an invariant that row variables are never shared between different types. That is, if row_more row1 == row_more row2, then row1 and row2 come from structurally identical Tvariants (but they might not be physically equal). When copying types, two types with the same row_more field are replaced by the same copy.

See documentation for row_more.

get all fields at once; different from the old row_repr

Current contents of a row field

see Typedecl_separability for an explanation of separability and separability modes.

This type tracks the distinction between legacy records ({ field }) and unboxed records (#{ field }). Note that Legacy includes normal boxed records, as well as inlined and [@@unboxed] records.

As a GADT, it also lets us avoid duplicating functions that handle both record forms, such as Env.find_label_by_name, which has type 'rep record_form -> Longident.t -> Env.t -> 'rep gen_label_description.

Extracts the list of "value" identifiers bound by a signature. "Value" identifiers are identifiers for signature components that correspond to a run-time value: values, extensions, modules, classes. Note: manifest primitives do not correspond to a run-time value!

Like bound_value_identifiers, but also return sorts

check if a snapshot has been invalidated

also register changes to arbitrary references

Number of unification variables that have been linked so far. Used to estimate the "cost" of unification.