[Haskell-cafe] Data constructors versus types

I know nothing about theoretical computer science, but I was wondering if it possible to forget about types, and just keep the concept of data constructors, and have an analyzer determine correctness of the code and "staticness" of the data? Basically this is what SCHEME does no? Doesn't SCHEME have static whole program analyzers to remove the overhead of the "symbol tags" and check correctness of a program (Stalin, Petit-Scheme, ...)? What are to pros/contras? Thank you, Peter