[Haskell-cafe] what are correct ways to translate haskell code ?
Jeffrey Brown
jeffbrown.the at gmail.com
Wed May 24 13:40:30 UTC 2023
> Maybe it should somehow replace "osiudfhg" with "x1_of", but how is it
supposed to know that? It is a library function, after all.
My understanding was that the user would ask for a refactoring by
explaining the isomorphism between two data types.
I just remembered that Facebook open-sourced something called Retrie that
they use to refactor their own Haskell code. That should give a solid lower
bound on what is possible.
On Wed, May 24, 2023 at 8:02 AM MigMit <migmit at gmail.com> wrote:
> I don't think that's possible. Assume that there is a library that
> contains a module Stupid with a function osiudfhg, which is actually the
> same as fst:
>
> module Stupid where
> osiudfhg :: (a, b) -> a
> osiudfhg (a, _) = a
>
> If Alice uses that library, then her code could look like
>
> main = putStrLn "print some magic number" >> print ( osiudfhg v )
>
> How is Bob's code supposed to look? Maybe it should somehow replace
> "osiudfhg" with "x1_of", but how is it supposed to know that? It is a
> library function, after all.
>
> Yes, it might analyze source code of the Stupid module, but this is a
> daunting task.
>
> > On 24 May 2023, at 14:52, profited--- via Haskell-Cafe <
> haskell-cafe at haskell.org> wrote:
> >
> > let's consider this example
> > Alice has 1.hs like this
> > v :: (,) Int Bool
> > v = (,) 0 False
> >
> > main :: IO ()
> > main = putStrLn "print some magic number" >> print ( fst
> v )
> >
> > Bob download 1.hs from Alice
> >
> > Bob would like to change 1.hs to 2.hs
> > Bob want the programs [ 1.hs 2.hs ] to behave the same
> >
> > the reason that Bob want to modify 1.hs may be
> > Bob does not like the type (,) in 1.hs
> >
> > Bob has Vector_2.hs
> > module Vector_2 where
> >
> > data Vector_2 a b = C a b
> >
> > x1_of :: Vector_2 a b -> a
> > x1_of ( C x1 _ ) = x1
> >
> > x2_of :: Vector_2 a b -> b
> > x2_of ( C _ x2 ) = x2
> >
> > Bob like his Vector_2.hs
> > Bob thinks the Vector_2 shall be good enough to replace (,) in
> 1.hs
> >
> > i want to create a translator.hs for Bob
> > Bob tell the translator.hs that Bob want to replace (,) with
> Vector_2 in 1.hs
> > translator.hs automatically translate 1.hs to 2.hs
> > 2.hs shall look like this
> > import Vector_2
> > ( Vector_2 )
> > import qualified Vector_2
> >
> > v :: Vector_2 Int Bool
> > v = Vector_2.C 0 False
> >
> > main :: IO ()
> > main = putStrLn "print some magic number" >> print (
> Vector_2.x1_of v )
> >
> > what shall i do ?
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--
Jeff Brown | Jeffrey Benjamin Brown
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