The idiomatic SML way to do such a thing, which Ur/Web inherits, is: datatype r = R of {LinkedCell : option r, ...} On 07/03/2015 10:11 AM, Gabriel Riba wrote: > Would it be difficult to support type recursion in records? > > > type r = {LinkedCell : option r, .....} > > > actually gives the error msg: > > "Unbound constructor variable r"