[Haskell-cafe] Examples of Mutually Recursive Types

[wren ng thornton]

Hugo Pacheco wrote:
> Hi all,
> I have been searching for examples of Haskell "real scenarios" that employ
> mutually recursive datatype definitions.
> Does anyone know some interesting libraries or structures that I could play
> with?

Tim Sheard presents a realistic use case in [1]. We're using it in a 
logic language compiler, though your definitions of realism may vary. 
There's an expanded version of the two-level types idea in [2].

[1] <http://web.cecs.pdx.edu/~sheard/papers/generic.ps>
[2] <http://web.cecs.pdx.edu/~sheard/papers/JfpPearl.ps>

-- 
Live well,
~wren