Make Envy the package of the week

Author: tfausak

content/issues/135.markdown

@@ -22,26 +22,27 @@ undefined
 
 -   [Battleship game online written in Haskell](https://np.reddit.com/r/haskell/comments/a12hwp/battleship_game_online_written_in_haskell/)
 -   [Cloud Haskell: High level redesign proposal](https://github.com/haskell-distributed/distributed-process/wiki/High-Level-Redesign-Proposal/f0ac67e3061c61244fdc32c642ce721541a19b0a)
--   [Counting the cost of colons in Haskell](https://www.fpcomplete.com/blog/2018/11/haskell-and-rust)
+-   [Counting the cost of colons in Haskell](https://neilmitchell.blogspot.com/2018/11/counting-cost-of-colons-in-haskell.html)
 -   [Cursors, part 2: The text cursor](https://cs-syd.eu/posts/2018-11-28-cursors-text)
 -   [Exploring Languages with Interpreters and Functional Programming](https://john.cs.olemiss.edu/~hcc/csci450/ELIFP/ExploringLanguages.html)
 -   [Formality is now able to fuse native datatypes](https://np.reddit.com/r/haskell/comments/a07sst/quick_update_formality_is_now_able_to_fuse_native/)
+-   [Haskell and Rust](https://www.fpcomplete.com/blog/2018/11/haskell-and-rust)
 -   [Haskell Bazaar: Explore Haskell and functional programming concepts](https://www.haskellbazaar.com)
 -   [Internal convention is a mistake](http://nikita-volkov.github.io/internal-convention-is-a-mistake/)
 -   [My favorite Haskell function](https://github.com/quchen/articles/blob/c8540f28bca2049b35f48d242988ca1ca248d0d8/2018-11-22_zipWith_const.md)
 -   [ozil: A help viewer for your terminal](https://np.reddit.com/r/haskell/comments/9zk41p/ozil_a_help_viewer_for_your_terminal/)
 -   [Parsing type-level strings in Haskell](https://kcsongor.github.io/symbol-parsing-haskell/)
 -   [The usefulness of maybe monad](https://www.youtube.com/watch?v=0F15o6_jGAs)
 -   [Tidal 1.0.0 refactor](https://slab.org/tidal-1-0-0-refactor/)
--   [todo](https://neilmitchell.blogspot.com/2018/11/counting-cost-of-colons-in-haskell.html)
 -   [Type Classes: The lessons continue](https://typeclasses.com/news/2018-11-lessons-continue)
 -   [Type-driven program synthesis](https://www.youtube.com/watch?v=HnOix9TFy1A)
 -   [Yo, Yoneda!](https://functional.works-hub.com/learn/yo-yoneda-a2965)
 -   [Yoneda intuition from humble beginnings](https://gist.github.com/Icelandjack/02069708bc75f4284ac625cd0e2ec81f/6cb8f671d5bbc8592557e5c7a5a5c224a9663973)
 
 ## Package of the week
 
-undefined
+This week's package of the week is [Envy](https://hackage.haskell.org/package/envy-1.5.1.0),
+a library for environmentally friendly environment variables.
 
 ## Call for participation