The history of Haskell has recently been published. It is a rather long read (55 pages), but a rewarding one. It covers how Haskell formed, decisions around why language constructs were introduced and surveys where it is at today.
Haskell was the second functional programming language I learnt. Miranda, my first, was the language used for first year programming at Melbourne Uni. Reading back on how Haskell split and evolved from Miranda filling in a lot of gaps for me.
There is also discussion on how Haskell has matured, stats on community growth, and case studies of commercial use. There is even a glimpse of the future:
One day, Haskell will be no more than a distant memory. But we believe that, when that day comes, the ideas and techniques that it nurtured will prove to have been of enduring value through their influence on languages of the future.