Static typing helps. Higher order programming helps. These are two reasons I love Haskell. The compiler does a lot of work of understanding your code for you,

Static typing helps. Higher order programming helps. These are two reasons I love Haskell. The compiler does a lot of work of understanding your code for you, and makes it easy to query that metadata interactively, and refer to it from other parts of static code. Haskell is of course not the only statically typed language, but its type system encompasses more, and more uniformly, than any other I am aware of. A lot of things that used to have to be part of the comments can now be first-class citizens.