[Haskell-cafe] GHCi gives type signature that won't compile.

2008-06-05 Thread A A 
Hi All

I can successfully compile the following code using ghci

import Data.Array.IArray

makeArray (lower, upper) f = listArray (lower, upper) [(f i) | i -
[lower..upper]
tridiagonal_solve (a, b, c, d, (lower, upper)) = x
where
gen_array f = (makeArray (lower, upper) f)
x = gen_array x_f
where
x_f i
| i == upper = (d_dash ! upper)
| otherwise = (d_dash ! i) - (c_dash ! i) * (x !
(i + 1))
d_dash = gen_array d_dash_f
where
d_dash_f i
| i == lower = (d ! lower) / (b ! lower)
| otherwise= ((d ! i) - (d_dash ! (i - 1)) * (a
! i)) /
  ((b ! i) - (c_dash ! (i - 1)) * (a
! i))
c_dash = gen_array c_dash_f
where
c_dash_f i
| i == lower= (c ! lower) / (b ! lower)
| otherwise = (c ! i) /
  ((b ! i) - (c_dash ! (i - 1)) * (a
! i))

I then attempted to write a type signature for tridiagonal_solve. I didn't
succeed at this however, all of my type signatures gave compile errors when
attempting to load them in ghci. I asked in the #haskell channel, and they
suggested that I try the type signature from ghci :type function.

So I removed any type signatures, and reloaded the file in ghci, and typed
:type tridiagonal_solve which produced the following output:

tridiagonal_solve :: (IArray a3 e,
  IArray a6 e,
  IArray a7 e,
  Fractional e,
  Ix a,
  Num a,
  IArray a4 e,
  IArray a2 e,
  IArray a5 e,
  IArray a1 e,
  Enum a) =
 (a4 a e, a2 a e, a1 a e, a5 a e, (a, a)) - a7 a e

I then attempted to paste this into my code, the resulting code looking like
this:

import Data.Array.IArray

makeArray (lower, upper) f = listArray (lower, upper) [(f i) | i -
[lower..upper]]

tridiagonal_solve :: (IArray a3 e,
  IArray a6 e,
  IArray a7 e,
  Fractional e,
  Ix a,
  Num a,
  IArray a4 e,
  IArray a2 e,
  IArray a5 e,
  IArray a1 e,
  Enum a) =
 (a4 a e, a2 a e, a1 a e, a5 a e, (a, a)) - a7 a e

tridiagonal_solve (a, b, c, d, (lower, upper)) = x
where
gen_array f = (makeArray (lower, upper) f)
x = gen_array x_f
where
x_f i
| i == upper = (d_dash ! upper)
| otherwise= (d_dash ! i) - (c_dash ! i) * (x !
(i + 1))
d_dash = gen_array d_dash_f
where
d_dash_f i
| i == lower = (d ! lower) / (b ! lower)
| otherwise= ((d ! i) - (d_dash ! (i - 1)) * (a
! i)) /
  ((b ! i) - (c_dash ! (i - 1)) * (a
! i))
c_dash = gen_array c_dash_f
where
c_dash_f i
| i == lower= (c ! lower) / (b ! lower)
| otherwise = (c ! i) /
  ((b ! i) - (c_dash ! (i - 1)) * (a
! i))

When I attempt to load this into ghci, I recieve the following error:

[1 of 1] Compiling Main ( main.lhs, interpreted )

main.lhs:29:11:
Could not deduce (IArray a1 e)
  from the context (IArray a3 e,
IArray a6 e,
IArray a7 e,
Fractional e,
Ix a2,
Num a2,
IArray a4 e,
IArray a21 e,
IArray a5 e,
IArray a11 e,
Enum a2)
  arising from a use of `gen_array' at main.lhs:29:11-28
Possible fix:
  add (IArray a1 e) to the context of
the type signature for `tridiagonal_solve'
In the expression: gen_array d_dash_f
In the definition of `d_dash':
d_dash = gen_array d_dash_f
   where
   d_dash_f i | i == lower = (d ! lower) / (b ! lower)
  | otherwise
  = ((d ! i) - (d_dash ! (i - 1)) * (a ! i))
  / ((b ! i) - (c_dash ! (i - 1)) * (a ! i))
In the definition of `tridiagonal_solve':
tridiagonal_solve (a, b, c, d, (lower, upper))
= x
where
gen_array f = (makeArray (lower, upper) f)
x = gen_array x_f
  where

Re: [Haskell-cafe] GHCi gives type signature that won't compile.

2008-06-05 Thread Miguel Mitrofanov 

Check your types for typos.

On 5 Jun 2008, at 20:31, A A wrote:


Hi All

I can successfully compile the following code using ghci

import Data.Array.IArray

makeArray (lower, upper) f = listArray (lower, upper) [(f i) | i -  
[lower..upper]

tridiagonal_solve (a, b, c, d, (lower, upper)) = x
where
gen_array f = (makeArray (lower, upper) f)
x = gen_array x_f
where
x_f i
| i == upper = (d_dash ! upper)
| otherwise = (d_dash ! i) - (c_dash !  
i) * (x ! (i + 1))

d_dash = gen_array d_dash_f
where
d_dash_f i
| i == lower = (d ! lower) / (b ! lower)
| otherwise= ((d ! i) - (d_dash ! (i -  
1)) * (a ! i)) /
  ((b ! i) - (c_dash ! (i -  
1)) * (a ! i))

c_dash = gen_array c_dash_f
where
c_dash_f i
| i == lower= (c ! lower) / (b ! lower)
| otherwise = (c ! i) /
  ((b ! i) - (c_dash ! (i -  
1)) * (a ! i))


I then attempted to write a type signature for tridiagonal_solve. I  
didn't succeed at this however, all of my type signatures gave  
compile errors when attempting to load them in ghci. I asked in the  
#haskell channel, and they suggested that I try the type signature  
from ghci :type function.


So I removed any type signatures, and reloaded the file in ghci, and  
typed :type tridiagonal_solve which produced the following output:


tridiagonal_solve :: (IArray a3 e,
  IArray a6 e,
  IArray a7 e,
  Fractional e,
  Ix a,
  Num a,
  IArray a4 e,
  IArray a2 e,
  IArray a5 e,
  IArray a1 e,
  Enum a) =
 (a4 a e, a2 a e, a1 a e, a5 a e, (a, a)) - a7  
a e


I then attempted to paste this into my code, the resulting code  
looking like this:


import Data.Array.IArray

makeArray (lower, upper) f = listArray (lower, upper) [(f i) | i -  
[lower..upper]]


tridiagonal_solve :: (IArray a3 e,
  IArray a6 e,
  IArray a7 e,
  Fractional e,
  Ix a,
  Num a,
  IArray a4 e,
  IArray a2 e,
  IArray a5 e,
  IArray a1 e,
  Enum a) =
 (a4 a e, a2 a e, a1 a e, a5 a e, (a, a)) - a7  
a e


tridiagonal_solve (a, b, c, d, (lower, upper)) = x
where
gen_array f = (makeArray (lower, upper) f)
x = gen_array x_f
where
x_f i
| i == upper = (d_dash ! upper)
| otherwise= (d_dash ! i) - (c_dash ! i)  
* (x ! (i + 1))

d_dash = gen_array d_dash_f
where
d_dash_f i
| i == lower = (d ! lower) / (b ! lower)
| otherwise= ((d ! i) - (d_dash ! (i -  
1)) * (a ! i)) /
  ((b ! i) - (c_dash ! (i -  
1)) * (a ! i))

c_dash = gen_array c_dash_f
where
c_dash_f i
| i == lower= (c ! lower) / (b ! lower)
| otherwise = (c ! i) /
  ((b ! i) - (c_dash ! (i -  
1)) * (a ! i))


When I attempt to load this into ghci, I recieve the following error:

[1 of 1] Compiling Main ( main.lhs, interpreted )

main.lhs:29:11:
Could not deduce (IArray a1 e)
  from the context (IArray a3 e,
IArray a6 e,
IArray a7 e,
Fractional e,
Ix a2,
Num a2,
IArray a4 e,
IArray a21 e,
IArray a5 e,
IArray a11 e,
Enum a2)
  arising from a use of `gen_array' at main.lhs:29:11-28
Possible fix:
  add (IArray a1 e) to the context of
the type signature for `tridiagonal_solve'
In the expression: gen_array d_dash_f
In the definition of `d_dash':
d_dash = gen_array d_dash_f
   where
   d_dash_f i | i == lower = (d ! lower) / (b ! lower)
  | otherwise
  = ((d ! i) - (d_dash ! (i - 1)) * (a !  
i))
  / ((b ! i) - (c_dash ! (i - 1)) * (a !  
i))

In the definition of `tridiagonal_solve':
tridiagonal_solve (a, b, c, d, (lower, upper))
= x
where
gen_array f = (makeArray

Re: [Haskell-cafe] GHCi gives type signature that won't compile.

2008-06-05 Thread Philip Weaver 
On Thu, Jun 5, 2008 at 9:36 AM, Miguel Mitrofanov [EMAIL PROTECTED] wrote:
 Check your types for typos.

 On 5 Jun 2008, at 20:31, A A wrote:

 Hi All

 I can successfully compile the following code using ghci

 import Data.Array.IArray

 makeArray (lower, upper) f = listArray (lower, upper) [(f i) | i -
 [lower..upper]
 tridiagonal_solve (a, b, c, d, (lower, upper)) = x
where
gen_array f = (makeArray (lower, upper) f)
x = gen_array x_f
where
x_f i
| i == upper = (d_dash ! upper)
| otherwise = (d_dash ! i) - (c_dash ! i) * (x
 ! (i + 1))
d_dash = gen_array d_dash_f
where
d_dash_f i
| i == lower = (d ! lower) / (b ! lower)
| otherwise= ((d ! i) - (d_dash ! (i - 1)) * (a
 ! i)) /
  ((b ! i) - (c_dash ! (i - 1)) *
 (a ! i))
c_dash = gen_array c_dash_f
where
c_dash_f i
| i == lower= (c ! lower) / (b ! lower)
| otherwise = (c ! i) /
  ((b ! i) - (c_dash ! (i - 1)) *
 (a ! i))

 I then attempted to write a type signature for tridiagonal_solve. I didn't
 succeed at this however, all of my type signatures gave compile errors when
 attempting to load them in ghci. I asked in the #haskell channel, and they
 suggested that I try the type signature from ghci :type function.

 So I removed any type signatures, and reloaded the file in ghci, and typed
 :type tridiagonal_solve which produced the following output:

 tridiagonal_solve :: (IArray a3 e,
  IArray a6 e,
  IArray a7 e,
  Fractional e,
  Ix a,
  Num a,
  IArray a4 e,
  IArray a2 e,
  IArray a5 e,
  IArray a1 e,
  Enum a) =
 (a4 a e, a2 a e, a1 a e, a5 a e, (a, a)) - a7 a e

 I then attempted to paste this into my code, the resulting code looking
 like this:

 import Data.Array.IArray

 makeArray (lower, upper) f = listArray (lower, upper) [(f i) | i -
 [lower..upper]]

 tridiagonal_solve :: (IArray a3 e,
  IArray a6 e,
  IArray a7 e,
  Fractional e,
  Ix a,
  Num a,
  IArray a4 e,
  IArray a2 e,
  IArray a5 e,
  IArray a1 e,
  Enum a) =
 (a4 a e, a2 a e, a1 a e, a5 a e, (a, a)) - a7 a e

 tridiagonal_solve (a, b, c, d, (lower, upper)) = x
where
gen_array f = (makeArray (lower, upper) f)
x = gen_array x_f
where
x_f i
| i == upper = (d_dash ! upper)
| otherwise= (d_dash ! i) - (c_dash ! i) * (x !
 (i + 1))
d_dash = gen_array d_dash_f
where
d_dash_f i
| i == lower = (d ! lower) / (b ! lower)
| otherwise= ((d ! i) - (d_dash ! (i - 1)) * (a
 ! i)) /
  ((b ! i) - (c_dash ! (i - 1)) *
 (a ! i))
c_dash = gen_array c_dash_f
where
c_dash_f i
| i == lower= (c ! lower) / (b ! lower)
| otherwise = (c ! i) /
  ((b ! i) - (c_dash ! (i - 1)) *
 (a ! i))

 When I attempt to load this into ghci, I recieve the following error:

 [1 of 1] Compiling Main ( main.lhs, interpreted )

 main.lhs:29:11:
Could not deduce (IArray a1 e)
  from the context (IArray a3 e,
IArray a6 e,
IArray a7 e,
Fractional e,
Ix a2,
Num a2,
IArray a4 e,
IArray a21 e,
IArray a5 e,
IArray a11 e,
Enum a2)
  arising from a use of `gen_array' at main.lhs:29:11-28
Possible fix:
  add (IArray a1 e) to the context of
the type signature for `tridiagonal_solve'
In the expression: gen_array d_dash_f
In the definition of `d_dash':
d_dash = gen_array d_dash_f
   where
   d_dash_f i | i == lower = (d ! lower) / (b ! lower)
  | otherwise
  = ((d ! i) - (d_dash ! (i - 1)) * (a ! i))
  / ((b ! i) - (c_dash ! (i - 1)) * (a ! i))
In the definition of `tridiagonal_solve':
tridiagonal_solve (a, b, c, d, (lower, upper))
= x
where