How to update a dependency

This doc walks through the process of updating a dependency, using Unison's standard library,base,as an example.

Suggested workflow summary:

    • pullthe latest version of the dependency into your codebase so that it is a sibling of your current library version
      • .myProject> pull unison.public.base.latest lib.newBase
    • Apply thepatchfrom the new version of the library to the project
      • patch lib.newBase.patch
    • Check if there aretodoitems in your project as a result of applying the patch
      • .myProject> todo
    • Delete the old version of base from your codebase.
      • .myProject> delete.namespace lib.base
    • Rename the new version of base tobase
      • .myProject> move.namespace lib.newBase lib.base

First,pullthe new version of the library into thelibnamespace of your project. It shouldnotbe pulled into the same namespace as your existing library version. Instead, give the new version a distinct name, likebaseV2ornewBase.We can change the name later.

Then apply the the patch from the new library version to the project. Assuming your UCM console is located at the top of your project, you can use the patch command like so:

.myProject> patch lib.newBase.patch

Patches map old term references to new references in a namespace; they're part of what helps Unison automatically propagate changes when functions get updated. Patch entries are created automatically when the library author runsupdate.

Next you should check if there aretodoitems in your project as a result of applying the patch. At the root of your project, runtodo:

.myProject> todo

Todo items can happen if a function in your project depends on a function in the library whose type signature has changed in the new version. If there aretodoitems after applying the patch, the UCM should supply a suggested order to tackle them in. You'll want to edit the terms into a scratch file, resolve the conflicts and thenupdatethe terms.

Once there are notodoitems it's safe to delete the old library version from thelibnamespace of the project. You may want to rename your new library version tobaseagain so that it's easier to refer to in the future.

.myProject> delete.namespace lib.base
.myProject> rename.namespace lib.newBase lib.base

It's done! Your project is now using the latest version of the dependency!