Standard ML (or golfier: SML) is a general-purpose, modular, functional programming language with compile-time type checking and type inference. (from Wikipedia)
Though you almost certainly will never win a code golf challenge with SML, (ab-) using it for golfing can nevertheless be quite
fun (<- keyword for function declaration). So without further ado ...
What tips do you have for golfing in Standard ML?
Please only post tips which are somewhat unique to SML. General golfing tips belong to Tips for golfing in all languages.