[Haskell] pros and cons of static typing and side effects ?

[mt]

> i can quote someone from this list: "if haskell compiler allow my
> program to be compiled then i know that there is no more errors in
> it". static typing is just an instrument which catches much more
> programmers' errors. static typing don't allow more programs tobe
> compiled - conversely, it prohibits a part of programs/techniques. but
> if you want to WORK, not hack - that is a right way
>

yes, that's the kind of answer i expected... that's the kind of thing you 
always see when reading something about haskell. but i guess there's 
arguments against... i'd like to make my opinion without just reading
a post saying "it catches many errors". maybe this mailing list is not the 
right place to ask this question ;-) maybe i should ask on a lisp mailing 
list :)

>
> m> Same question for (direct support of) side effects.
>
> it's just because Haskell is a lazy language. this rises expresivness
> and strongly divides program to two parts - without side effects and
> with side effects

the way it's divided is to remain purely functional. would it be bad if the 
side effects part was designed without keeping a pure functional language ?

i see sometimes this kind of arg : it's easier to reason with a pure 
functional semantic. is this hold when you have to program a fair amount of 
imperative code in haskell?

in fact my first question was not haskell centric but more general, like if i 
wanted to design a new language, not like if i wondered which language to 
choose.

regards,
mt