https://github.com/purescript/purescript/wiki/Differences-from-Haskell
...says:
> Since 0.9.1, the Prelude library does not contain (++) as a second alias for append / (<>) (mappend in Haskell) anymore.
So:
```
-- Concatenate
"such " ++ "amaze" -- "such amaze"
```
...should read:
```
-- Concatenate
"such " <> "amaze" -- "such amaze"
```