package diff

  1. Overview
  2. Docs
A library for generating diffs from product types

Install

Dune Dependency

Authors

Maintainers

Sources

1.0.2.tar.gz
md5=6316048a1c65fa28a0ee71fa1450d87c
sha512=07d1be5825e00f6d10e6c9d175ef7cc300dc6b8993d91004817d4dc086298798fe7d017b8024d1c1b62d35fbf091077c1fb518418c7f1039e3e071ef07db0f5a

Description

Published: 24 Oct 2023

README

diff

An OCaml library for generating diffs of product types.

Example

type t = { foo : int; bar : string; }
[@@deriving diff]

let spec = Diff.many [
  Diff.leaf ~field:Foo ~equal:Int.equal;
  Diff.leaf ~field:Bar ~equal:String.equal;
]

let () =
  let t0 = { foo = 1; bar = "Skolem" } in
  let t1 = { foo = 1; bar = "OCaml" } in
  let diff = Diff.compute t0 t1 spec in
  let t0' = Diff.apply_all t0 diff in
  assert (t0' = t1)

Usage

The main use case of this library is to version records without having to keep a copy of each version around.

The library includes a ppx for generating field accessors from records. To use the ppx with dune, add it to the preprocessing field of your stanza:

(library
 (name mylib)
 ...
 (preprocessing (pps diff.ppx)))

In order to actually compute diffs, you need to write a spec for how your record should be traversed. There are functions provided to help you do so:

  • leaf ~field ~equal represents a "terminal" node in the spec tree, i.e. the diffing algorithm should simply compare the field values and add it to the diff list if they are different.

  • child ~field ~spec represents an "intermediate" node in the spec tree, i.e. the diffing algorithm should recursively compute the diff of a "child" record.

  • opt_child ~field ~spec reprents an optional intermediate node in the spec tree, i.e. a child record that is optional in the parent.

  • many specs: flattens many specs into a single one.

For more usage examples, check out example/example.ml and tests/*_test.ml.

License

This project is licensed under the MIT License.

Dependencies (3)

  1. ppxlib >= "0.26.0"
  2. ocaml >= "4.08.0"
  3. dune >= "3.10"

Dev Dependencies (4)

  1. odoc with-doc
  2. tezt with-test & >= "3.1.1" & < "4.0.0"
  3. ppx_deriving with-test
  4. ocamlformat with-dev-setup

Used by

None

Conflicts

None

OCaml

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