{"action":"created","issue":{"url":"https://api.github.com/repos/typelevel/cats/issues/872","repository_url":"https://api.github.com/repos/typelevel/cats","labels_url":"https://api.github.com/repos/typelevel/cats/issues/872/labels{/name}","comments_url":"https://api.github.com/repos/typelevel/cats/issues/872/comments","events_url":"https://api.github.com/repos/typelevel/cats/issues/872/events","html_url":"https://github.com/typelevel/cats/issues/872","id":132721007,"number":872,"title":"add Unfoldable typeclass","user":{"login":"julien-truffaut","id":1859417,"avatar_url":"https://avatars.githubusercontent.com/u/1859417?v=3","gravatar_id":"","url":"https://api.github.com/users/julien-truffaut","html_url":"https://github.com/julien-truffaut","followers_url":"https://api.github.com/users/julien-truffaut/followers","following_url":"https://api.github.com/users/julien-truffaut/following{/other_user}","gists_url":"https://api.github.com/users/julien-truffaut/gists{/gist_id}","starred_url":"https://api.github.com/users/julien-truffaut/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/julien-truffaut/subscriptions","organizations_url":"https://api.github.com/users/julien-truffaut/orgs","repos_url":"https://api.github.com/users/julien-truffaut/repos","events_url":"https://api.github.com/users/julien-truffaut/events{/privacy}","received_events_url":"https://api.github.com/users/julien-truffaut/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":2,"created_at":"2016-02-10T14:58:33Z","updated_at":"2016-02-11T11:07:50Z","closed_at":null,"body":"see https://github.com/purescript/purescript-unfoldable/blob/master/docs/Data/Unfoldable.md"},"comment":{"url":"https://api.github.com/repos/typelevel/cats/issues/comments/182811634","html_url":"https://github.com/typelevel/cats/issues/872#issuecomment-182811634","issue_url":"https://api.github.com/repos/typelevel/cats/issues/872","id":182811634,"user":{"login":"julien-truffaut","id":1859417,"avatar_url":"https://avatars.githubusercontent.com/u/1859417?v=3","gravatar_id":"","url":"https://api.github.com/users/julien-truffaut","html_url":"https://github.com/julien-truffaut","followers_url":"https://api.github.com/users/julien-truffaut/followers","following_url":"https://api.github.com/users/julien-truffaut/following{/other_user}","gists_url":"https://api.github.com/users/julien-truffaut/gists{/gist_id}","starred_url":"https://api.github.com/users/julien-truffaut/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/julien-truffaut/subscriptions","organizations_url":"https://api.github.com/users/julien-truffaut/orgs","repos_url":"https://api.github.com/users/julien-truffaut/repos","events_url":"https://api.github.com/users/julien-truffaut/events{/privacy}","received_events_url":"https://api.github.com/users/julien-truffaut/received_events","type":"User","site_admin":false},"created_at":"2016-02-11T11:07:50Z","updated_at":"2016-02-11T11:07:50Z","body":"I guess we can express the first \"law\" if we assume `F` to have a `Foldable` instance:\r\n\r\n```\r\nforAll{b: B =>\r\n  unfoldr(_ => None)(b).isEmpty \r\n}\r\n```\r\n\r\nfor the second one, we would need some notion of `Cons` for `F`"}}