[Haskell-cafe] Slightly off-topic: Lambda calculus

Andrew Coppin andrewcoppin at btinternet.com
Sun Jun 21 14:48:30 EDT 2009

Andrew Coppin wrote:
> Well anyway, the obvious thing to do is after each reduction, strip 
> off all the variable indicies and rerun the labeller to assign new 
> indicies. But does this solution work properly in general?


Supposing some Lambda expression eventually reduces to, say,

  \x1 -> \x2 -> x1 x2

Now strip off all the indicies:

  \x -> \x -> x x

...and recompute them...

  \x1 -> \x2 -> x2 x2


To make it worth properly, I would have to (at least) make the renamer 
respect any indicies which are already present. It's nontrivial, but 
doable. Of course, the £1,643,264 question is... would it work even then?

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