Boolean logic is central to many business rules. But sometimes it’s not enough to know whether a chain of conditions evaluates to true
or false
; we might want to know which of the conditions failed. F#, unsurprisingly, lets us model this in a very succinct, composable, and completely type-safe way. But there are pitfalls – sometimes, a seemingly simple and pure function just won’t cut it.
F# tip: Tell the user which condition failed
Let F# types guide you to better user experiences and stopping terrorists.