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Today's Topics:
1. Overload ^ (trent shipley)
2. Re: Overload ^ (Paul)
----------------------------------------------------------------------
Message: 1
Date: Fri, 2 Mar 2018 23:24:28 -0700
From: trent shipley <trent.ship...@gmail.com>
To: beginners@haskell.org
Subject: [Haskell-beginners] Overload ^
Message-ID:
<CAEFLyb+Jff8UuQ3RMj+n17WuvAnwaQGdJPXyG=hmdumbdzd...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
{-
I want to override Prelude.^ (as an academic exercise).
Can it be done? How?
Trent
-}
(^) :: Int -> Int -> Int
m ^ 0 = 1
m ^ n = m * (m ^ (n-1))
{-
Hutton, Graham. Programming in Haskell (p. 263). Cambridge University
Press. Kindle Edition. 2016.
-}
{-
Result
[1 of 1] Compiling Main ( ex6_3b.hs, interpreted )
ex6_3b.hs:3:16: error:
Ambiguous occurrence ‘^’
It could refer to either ‘Prelude.^’,
imported from ‘Prelude’ at ex6_3b.hs:1:1
(and originally defined in ‘GHC.Real’)
or ‘Main.^’, defined at ex6_3b.hs:2:3
|
3 | m ^ n = m * (m ^ (n-1)) | ^
Failed, no modules loaded.
-}
-- So I try
(^) :: Int -> Int -> Int
m Main.^ 0 = 1
m Main.^ n = m * (m Main.^ (n-1))
{-
Result
Prelude> :reload
ex6_3b.hs:2:3: error: Qualified name in binding position: Main.^
|
2 | m Main.^ 0 = 1 | ^^^^^^
[1 of 1] Compiling Main ( ex6_3b.hs, interpreted )
Failed, no modules loaded.
-}
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Message: 2
Date: Sat, 3 Mar 2018 08:33:11 +0200
From: Paul <aqua...@gmail.com>
To: The Haskell-Beginners Mailing List - Discussion of
primarilybeginner-level topics related to Haskell
<beginners@haskell.org>
Subject: Re: [Haskell-beginners] Overload ^
Message-ID: <5a9a41a5.5198df0a.8d5ff.5...@mx.google.com>
Content-Type: text/plain; charset="utf-8"
import Prelude hiding ((^))
See here: https://wiki.haskell.org/Import
Best regards,
Paul
От: trent shipley
Отправлено: 3 марта 2018 г. в 8:25
Кому: beginners@haskell.org
Тема: [Haskell-beginners] Overload ^
{-
I want to override Prelude.^ (as an academic exercise).
Can it be done? How?
Trent
-}
(^) :: Int -> Int -> Int
m ^ 0 = 1
m ^ n = m * (m ^ (n-1))
{-
Hutton, Graham. Programming in Haskell (p. 263). Cambridge University Press.
Kindle Edition. 2016.
-}
{-
Result
[1 of 1] Compiling Main ( ex6_3b.hs, interpreted )
ex6_3b.hs:3:16: error:
Ambiguous occurrence ‘^’
It could refer to either ‘Prelude.^’,
imported from ‘Prelude’ at ex6_3b.hs:1:1
(and originally defined in ‘GHC.Real’)
or ‘Main.^’, defined at ex6_3b.hs:2:3
|
3 | m ^ n = m * (m ^ (n-1)) | ^
Failed, no modules loaded.
-}
-- So I try
(^) :: Int -> Int -> Int
m Main.^ 0 = 1
m Main.^ n = m * (m Main.^ (n-1))
{-
Result
Prelude> :reload
ex6_3b.hs:2:3: error: Qualified name in binding position: Main.^
|
2 | m Main.^ 0 = 1 | ^^^^^^
[1 of 1] Compiling Main ( ex6_3b.hs, interpreted )
Failed, no modules loaded.
-}
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