I was writing a script on gretl (CVS version, couple of days old).

I get the following

gretl version 1.8.6cvs
Current session: 2010-01-11 17:56
? scalar testdot = 0.1
Replaced scalar testdot = 0
? print testdot

testdot = 0,00000000
? scalar testdiv = 1/10
Generated scalar testdiv = 0,1
? print testdiv

testdiv = 0,10000000
? scalar testcomma = 0,1

> scalar testcomma = 0,
The symbol ',' is not valid in this context
Syntax error in command line

Error executing script: halting
> scalar testcomma = 0,1

I'm forced to use set force_decpoint on and use a dot for anything to work. This isn't, I think, the best behaviour. If you have a script with an

if xxx > 0.1

you will have very different results, and no warning, depending on the locale setting. And if this is indeed the desired behaviour then the comma as a separator should work fine.