package octez-proto-libs

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Octez protocol libraries

Install

Dune Dependency

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Authors

T

Tezos devteam

Maintainers

C

contact@tezos.com

Sources

tezos-18.0.tar.gz

sha256=dbc3b675aee59c2c574e5d0a771193a2ecfca31e7a5bc5aed66598080596ce1c

sha512=b97ed762b9d24744305c358af0d20f394376b64bfdd758dd4a81775326caf445caa57c4f6445da3dd6468ff492de18e4c14af6f374dfcbb7e4d64b7b720e5e2a

doc/octez-proto-libs.protocol-environment/Tezos_protocol_environment/V10/Make/Equality_witness/index.html

Module `Make.Equality_witness`Source

This module provides support for type equalities and runtime type identifiers.

For two types a and b, (a, b) eq is a witness that a = b. This is a standard generalized algebraic datatype on top of which type-level programming techniques can be implemented.

Given a type a, an inhabitant of a t is a dynamic identifier for a. Identifiers can be compared for equality. They are also equipped with a hash function.

WARNING: the hash function changes at every run. Therefore, the result of the hash function should never be stored.

Notice that dynamic identifiers are not unique: two identifiers for a can have distinct hash and can be physically distinct. Hence, only eq can decide if two type identifiers correspond to the same type.

Sourcetype (_, _) eq =

| Refl : ('a, 'a) eq

A proof witness that two types are equal.

Sourcetype 'a t

A dynamic representation for 'a.

Sourceval make : unit -> 'a t

make () is a dynamic representation for 'a. A fresh identifier is returned each time make () is evaluated.

Sourceval eq : 'a t -> 'b t -> ('a, 'b) eq option

eq ida idb returns a proof that a = b if ida and idb identify the same type.

Sourceval hash : 'a t -> int

hash id returns a hash for id.