[Haskell-cafe] Naturality condition for inits

[J.N. Oliveira]

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

    http://linux.tcs.inf.tu-dresden.de/~voigt/ft

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

jno