[MLton] it is necessary to manually make things tail-recursive?

[skaller]

Just a red herring .. but in a purely functional language (which doesn't
include ML ..) it isn't clear there's any benefit from tail rec.

Reusing a stack frame 'under the covers' turns out to be a serious
problem in a multiprocessing environment because it interferes
with parallel garbage collection. 

At best you can avoid storing inner return addresses.

It turns out you can also do this in some non-tail recursive
routines.

-- 
John Skaller <skaller at users dot sf dot net>
Felix, successor to C++: http://felix.sf.net