[Haskell-cafe] Are there standard idioms for lazy, pure error handling?

wren ng thornton wren at freegeek.org
Fri Dec 4 09:21:13 EST 2009

wren ng thornton wrote:
> One of the nice things about not having a Nil is that it lets you easily 
> be polymorphic over things ending in () ---a normal list---, (Maybe a) 
> ---a fallible list---, (Either a b) ---your progress type---, etc. 
> Whereas the version that has both Nil and End forces us into the (Maybe 
> a) scenario. A side effect of this is that the (Either a b) option isn't 
> available because we can only construct t=Mx.(x*t)+(1+a+b) not 
> t=Mx.(x*t)+(a+b).

Er, I meant t=Mx.(c*x)+(1+a+b) vs t=Mx.(c*x)+(a+b). This is what I get 
for posting without coffee.

Live well,

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