Proposal: Add a strict version of <$> for monads

Johan Tibell johan.tibell at
Fri Nov 29 15:35:24 UTC 2013

I'm trying to figure out whether this is a property of the functor itself.
I guess it is, but at the same time it seems somewhat orthogonal whether to
`seq` some value`.

On Fri, Nov 29, 2013 at 3:50 PM, Twan van Laarhoven <twanvl at>wrote:

> On 29/11/13 12:23, Johan Tibell wrote:
>> On Fri, Nov 29, 2013 at 1:19 PM, Twan van Laarhoven <twanvl at
>> <mailto:twanvl at>> wrote:
>>     I don't like that this function is implemented for Monads, I think
>> that it
>>     makes sense for some other functors as well. Though to do this
>> 'properly' we
>>     would probably end up with another typeclass "StrictFunctor" or
>> something,
>>     and that is perhaps too much unnecessary complexity.
>> Do you have an example of such a functor?
>> -- Johan
> The first thing that came to mind was ZipList. Perhaps a more realistic
> example would be parsing combinator or FRP libraries that are applicative
> but not monadic.
> Twan
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