[Haskell-cafe] fromInteger for Lists
pkeir at dcs.gla.ac.uk
Fri May 1 18:01:30 EDT 2009
There's nothing better than making a data type an instance of Num. In particular, fromInteger is a joy. But how about lists?
For example, if I have
data Foo a = F [a]
I can create a fromInteger such as
fromInteger i = F [fromInteger i]
and then a 19::(Foo Int), could become F .
Is it possible to do something similar for lists? So could
[1,2,3]::(Foo Int) become something slightly different, say,
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Haskell-Cafe