[Haskell-cafe] Naturality condition for inits

J.N. Oliveira jno at di.uminho.pt
Sun Mar 8 04:16:56 EDT 2009

R J wrote:

> Here's another Bird problem that's stymied me:
> The function "inits" computes the list of initial segments of a list; 
> its type is inits :: [a] -> [[a]].  What is the appropriate naturality 
> condition for "inits"?

Just use the free theorem associated to type [a] -> [[a]] in Janis 
Voigtlaender’s free theorem generator


and see the outcome when all permissible relation variables are 
functions (at the bottom of the screen).


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