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how to generalize these two map into one map

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  how to generalize these two map into one map Ho Yeung Lee <davidbenny2000@gmail.com> - 2016-07-26 22:08 -0700
    Re: how to generalize these two map into one map Mark Carroll <mtbc@bcs.org> - 2016-07-27 08:39 +0100
      Re: how to generalize these two map into one map meInvent bbird <jobmattcon@gmail.com> - 2016-07-27 02:17 -0700
        Re: how to generalize these two map into one map Mark Carroll <mtbc@bcs.org> - 2016-07-27 10:30 +0100
          Re: how to generalize these two map into one map meInvent bbird <jobmattcon@gmail.com> - 2016-07-27 20:20 -0700

#430 — how to generalize these two map into one map

import Data.Foldable
let aa = map (+1.2) [1,2]
let bb = map (+1.4) [2,3]

i find foldr, but how to use it for above two map?

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#431

On 27 Jul 2016, Ho Yeung Lee wrote:

> import Data.Foldable
> let aa = map (+1.2) [1,2]
> let bb = map (+1.4) [2,3]
>
> i find foldr, but how to use it for above two map?

I am not sure for what result you are hoping, but perhaps "zip" can
help?

-- Mark

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#432

i do not know result too, 
this is why i need to compile and run it to show this magic result


*Main Data.Foldable> foldr ((map (+1.2) [1,2]) . (map (+1.4) [2,3])) 1.0

<interactive>:18:1:
    Ambiguous occurrence `foldr'
    It could refer to either `Data.List.foldr',
                             imported from `Data.List' at trees3a.hs:1:1-16
                             (and originally defined in `GHC.Base')
                          or `Data.Foldable.foldr', imported from `Data.Foldable'
*Main Data.Foldable> foldr ((map (+1.2) [1,2]) . (map (+1.4) [2,3])) [1.0]

<interactive>:19:1:
    Ambiguous occurrence `foldr'
    It could refer to either `Data.List.foldr',
                             imported from `Data.List' at trees3a.hs:1:1-16
                             (and originally defined in `GHC.Base')
                          or `Data.Foldable.foldr', imported from `Data.Foldable'
*Main Data.Foldable> Data.Foldable.foldr ((map (+1.2) [1,2]) . (map (+1.4) [2,3])) [1.0]

<interactive>:20:23:
    Couldn't match expected type `b0 -> [t1] -> [t1]'
                with actual type `[b1]'
    In the return type of a call of `map'
    Probable cause: `map' is applied to too many arguments
    In the first argument of `(.)', namely `(map (+ 1.2) [1, 2])'
    In the first argument of `Data.Foldable.foldr', namely
      `((map (+ 1.2) [1, 2]) . (map (+ 1.4) [2, 3]))'

<interactive>:20:44:
    Couldn't match expected type `a0 -> b0' with actual type `[b2]'
    In the return type of a call of `map'
    Probable cause: `map' is applied to too many arguments
    In the second argument of `(.)', namely `(map (+ 1.4) [2, 3])'
    In the first argument of `Data.Foldable.foldr', namely
      `((map (+ 1.2) [1, 2]) . (map (+ 1.4) [2, 3]))'
*Main Data.Foldable> Data.Foldable.foldr ((map (+1.2) [1,2]) . (map (+1.4) [2,3])) [1.0,2.0]

<interactive>:21:23:
    Couldn't match expected type `b0 -> [t1] -> [t1]'
                with actual type `[b1]'
    In the return type of a call of `map'
    Probable cause: `map' is applied to too many arguments
    In the first argument of `(.)', namely `(map (+ 1.2) [1, 2])'
    In the first argument of `Data.Foldable.foldr', namely
      `((map (+ 1.2) [1, 2]) . (map (+ 1.4) [2, 3]))'

<interactive>:21:44:
    Couldn't match expected type `a0 -> b0' with actual type `[b2]'
    In the return type of a call of `map'
    Probable cause: `map' is applied to too many arguments
    In the second argument of `(.)', namely `(map (+ 1.4) [2, 3])'
    In the first argument of `Data.Foldable.foldr', namely
      `((map (+ 1.2) [1, 2]) . (map (+ 1.4) [2, 3]))'
*Main Data.Foldable> foldr ((map (+1.2) [1,2]) . (map (+1.4) [2,3])) [1.0,2.0]

<interactive>:22:1:
    Ambiguous occurrence `foldr'
    It could refer to either `Data.List.foldr',
                             imported from `Data.List' at trees3a.hs:1:1-16
                             (and originally defined in `GHC.Base')
                          or `Data.Foldable.foldr', imported from `Data.Foldable'
*Main Data.Foldable> foldr ((map (+1.2) [1,2]) . (map (+1.4) [2,3])) [1.0,2.0]


On Wednesday, July 27, 2016 at 3:39:24 PM UTC+8, Mark Carroll wrote:
> On 27 Jul 2016, Ho Yeung Lee wrote:
> 
> > import Data.Foldable
> > let aa = map (+1.2) [1,2]
> > let bb = map (+1.4) [2,3]
> >
> > i find foldr, but how to use it for above two map?
> 
> I am not sure for what result you are hoping, but perhaps "zip" can
> help?
> 
> -- Mark

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#433

On 27 Jul 2016, meInvent bbird wrote:

> i do not know result too, 
> this is why i need to compile and run it to show this magic result
>
> *Main Data.Foldable> foldr ((map (+1.2) [1,2]) . (map (+1.4) [2,3])) 1.0

Exactly what were you hoping that this would do, though?

-- Mark

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#436

i do not familiar with the syntax, 

what is the correct way to write for run it?


On Wednesday, July 27, 2016 at 5:30:56 PM UTC+8, Mark Carroll wrote:
> On 27 Jul 2016, meInvent bbird wrote:
> 
> > i do not know result too, 
> > this is why i need to compile and run it to show this magic result
> >
> > *Main Data.Foldable> foldr ((map (+1.2) [1,2]) . (map (+1.4) [2,3])) 1.0
> 
> Exactly what were you hoping that this would do, though?
> 
> -- Mark

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