Why Haskell is our first choice
Haskell is the first programming language we reach for when we build production software systems. This likely seems unusual to anyone who only has a passing familiarity with the language. Haskell has a reputation for being an advanced language with a steep learning curve. It is also often thought of as a research language with limited practical utility.
Source: Why Haskell is our first choice for building production software systems, an article by Christian Charukiewicz.