[Haskell-cafe] Haskell integration with C/C++ (GSOC)

[Holger Siegel]

Am 05.04.2012 um 08:42 schrieb Brandon Allbery:

> On Thu, Apr 5, 2012 at 01:53, Sutherland, Julian <julian.sutherland10 at imperial.ac.uk> wrote:
> data Tree = Node Left Right | Leaf
> 
> Could be converted to a struct in C/C++:
> 
> struct Tree {
>     struct Tree* left;
>     struct Tree* right;
> };
> 
> Shouldn't this actually be a tagged union?  Not that they exist as such in C/C++, but are easy enough to emulate (minus the extra type checking that real tagged unions such as even Pascal gives you):


Not necessarily. The above type is equivalent to

  type Tree = Maybe (Left, Right)

(modulo strictness, of course) and the C/C++ convention is to represent Nothing by a NULL pointer.