Lazy ML extension and signatures

Hello,

I had the problem, that I wanted to export a lazy datatype. I wanted to
mark it lazy, to use it outside in recursions without creating infinite
loops (for a small combinator library).

I thought of something like "type lazy foo" or "datatype lazy foo" in
the signature, but both don't work. Because I haven't found good
documentation of this issue, I thought I try my luck here. Hope this is
not documented somewhere and I simply overlooked it.

I want something like:

structure Foo : sig
  type lazy foo
end = struct
  datatype lazy foo = Foo of ... | Bar of ... | ...
end

(forgot to say, I tried it with SML/NJ 110.42 and SML/NJ 110.51)

-- 
Matthias Kretschmer


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