Hidden features of Haskell [closed]

Answer 1

Optional Layout

You can use explicit braces and semicolons instead of whitespace (aka layout) to delimit blocks.

let {
      x = 40;
      y = 2
     } in
 x + y

... or equivalently...

let { x = 40; y = 2 } in x + y

... instead of ...

let x = 40
    y = 2
 in x + y

Because layout is not required, Haskell programs can be straightforwardly produced by other programs.