Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Link to relevant Const doc from doc of Traverse #3065

Merged
merged 1 commit into from
Sep 16, 2019
Merged

Link to relevant Const doc from doc of Traverse #3065

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 2 additions & 0 deletions docs/src/main/tut/typeclasses/traverse.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -160,6 +160,8 @@ def foldMap[F[_]: Traverse, A, B: Monoid](fa: F[A])(f: A => B): B =
Traverse[F].traverse[Const[B, *], A, B](fa)(a => Const(f(a))).getConst
```

This works because `Const[B, *]` is an `Applicative` if `B` is a `Monoid`, as explained in [the documentation of `Const`](const.html#example-2-traverse).

## Further Reading

* [The Essence of the Iterator Pattern][iterator] - Gibbons, Oliveira. JFP 2009.
Expand Down