[Haskell-cafe] IO in lists

Yitzchak Gale gale at sefer.org
Wed Jan 17 03:07:18 EST 2007

I wrote:
>>> But the list monad [] is not a transformer, so you can't lift in it,
>>> even if the contained type happens also to be a monad.

Andrew Bromage wrote:
> ListT is also not a transformer.

True, unfortunately. But it does provide MonadTrans
and MonadIO instances that solve problems like
this in practice.

What can be done to get an improved list transformer
into MTL?

> See here for details:
>     http://www.haskell.org/hawiki/ListTDoneRight

Can someone with permissions on the new wiki please
get this important page moved over?


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