It is kind of a 0-length tuple, if you squint, though it's usually called "unit". Each tuple type is entirely distinct from each other, so there's nothing that indicates that something is a tuple except for the spelling -- (a,b,c). For example, unlike python, there is no way to determine the length of a tuple at runtime (e.g. length ()) nor iterate at runtime (as the types are heterogeneous). -Ross On Nov 6, 2009, at 5:08 PM, Pasqualino Titto Assini wrote:

Hi,

I just noticed that the json library maps () to a JSON empty array: [].

This makes sense if () is a 0-length tuple, the (2,"hi") tuple for example maps to [2,"hi"]

But is it so in Haskell?

In what sense () is a 0-length tuple?

Thanks,

titto _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe