Actually, the benefits of pure functional programming are even more clearly exposed if you're doing complex IO operations like disk access and mutability. The a

Actually, the benefits of pure functional programming are even more clearly exposed if you're doing complex IO operations like disk access and mutability. The ability to capture the effectful operations (read a table, write a row) as statically-typed action containers is invaluable because it lets you sequence the effects in a correct order with very little effort.