Re: [Haskell-cafe] run-time type testing in haskell?

On Sat, Apr 28, 2007 at 02:06:21PM +0100, Eric wrote:

In imperative languages one can test the type of a variable and downcast if necessary. Here's an example in Pseudojava:

T v := ... ; if (v instanceof T') T' v' := (T')v

Is it possible to do something like this in Haskell?

Possible, yes. Usually a good idea - no. Look at the Data.Typeable and Data.Dynamic modules in the standard hierarchal libraries. Stefan