Functional programming in ML

[EVS]

I have this datatype defined:

datatype 'a somedata = empty | data of string * string * 'a somedata list;

how could I write a function that would print this out?

I tried something like this :

fun print (empty) = [empty] | print (data(birka,vertiba,[somedata])) = print([somedata]); | printxml data(birka,vertiba,[empty]) = [empty];

thanks!

[EVS]

Another thing:

I hate to ask this, but is there a possibility to ASSIGN a value to a variable in a if-then construction? If-then is supposed to be an expression-operator, rather, than a statement. Does that make it like a function being able only to return values and not contain blocks of code?