Tidy up prelude (#66)

* Fix `apply` metadata in prelude

* Dial back health warning in readme.

* Prelude tidy-ups

Author: gmorpheme

README.md

@@ -2,8 +2,9 @@
 
 [![CircleCI](https://circleci.com/gh/curvelogic/eucalypt-hs.svg?style=svg&circle-token=97ae77777028be6a88a53b23b78d5c858a49ef33)](https://circleci.com/gh/curvelogic/eucalypt-hs)
 
-This is a prototype Haskell implementation of the Eucalypt language
-for generating, templating, rendering and processing structured data
+This is a Haskell implementation of the
+[eucalypt](https://curvelogic.github.io/eucalypt/) language for
+generating, templating, rendering and processing structured data
 formats like YAML and JSON.
 
 You need stack (`brew install haskell-stack`...)
@@ -20,10 +21,3 @@ To build and install the `eu` binary:
 ```
 stack install
 ```
-
-**Health warning**
-
-This implementation is currently a very crude substitutional
-interpreter for experimenting with the shape of the Eucalypt language.
-It has many shortcuts and shortcomings. It's not complete, nor
-necessarily even ready for casual use.