What on Earth? Record syntax has been around since the very first versions of Haskell. This is a surprisingly blatant error to see so near the beginning of this article…
Also, Haskell? You can take your space leaks and shove them.
In case any passers by are interested, space leaks are a solved problem: make invalid laziness unrepresentable (https://h2.jaguarpaw.co.uk/posts/make-invalid-laziness-unrep...)
...yet.