User defined statements for D like seed have?

[dennis luehring]

example how a for statement is declared
http://seed7.sourceforge.net/examples/declstat.htm

ok i know that seed is an interpreter language but maybe there is a way 
walter can allow something like this for his buildin statements

or even better the case statement

http://seed7.sourceforge.net/manual/stats.htm#case-statement

as a statement-template wich can produce (with the help of the awaited 
static foreach) a nice objectfactory from a tuple or something like this

ciao denni