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Today's Topics:
1. Re: Question on terminology (Kostiantyn Rybnikov)
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Message: 1
Date: Sun, 6 Mar 2016 13:04:51 +0200
From: Kostiantyn Rybnikov <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Question on terminology
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(f a b) still doesn't make a lot of sense, I assume (a -> b) was meant in
that argument type.
On Mar 3, 2016 21:13, "Rein Henrichs" <[email protected]> wrote:
> Ben, I just assumed that g was a typo for f.
>
> On Thu, Mar 3, 2016 at 10:10 AM Ben Rogalski <[email protected]> wrote:
>
>> I'm having trouble understanding this:
>>
>> > IIUC, one would describe fmap as "lifting" a function g into a functor
>> f,
>> > in the sense of
>> >
>> > Functor f => (g a b) -> g a -> g b
>> >
>> >
>> > Is there an inverse concept (? co-lift ?) that describes
>> >
>> > Functor f => (g a -> g b) -> a -> b
>> >
>>
>> It seems like these are type declarations for functions, with class
>> constraints that say f must be a Functor, but then f doesn't appear
>> anywhere else in the declaration. Why is this?
>>
>> Thanks,
>> -Ben
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