Hi Mark, What's the definition of foldr in terms of map? As far as I was aware, its not possible. And as it happens, map is (or is sometimes) defined in term of foldr :-) While you can use mutual recursion, you can't define a in terms of b and b in terms of a unless one of them actually does something at the end - so it does depend exactly what the definitions are. Thanks Neil 2009/3/16 Mark Spezzano :

Hi,

I’ve noticed that it’s possible to define map as foldr and foldr as a map. Would this be sensible to define both in terms of each other in the Prelude?  i.e mutually recursive?

Cheers,

Mark

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