Scheme sucks

Most Lisps specify an order of evaluation for procedure arguments. Scheme does not. Order of evaluation—including the order in which the expression in the operator position is evaluated—may be chosen by an implementation
that is why.

>>10
the fact that Haskell forces lazy evaluation and does not allow the option of non-lazy evaluation like ML does allows for far greater potential to optimise as the compiler can reason about the entire program in a lazy fashion.