Tom Pledger:
Brian Boutel writes:
:
| Having Units as types, with the idea of preventing adding Apples to
| Oranges, or Dollars to Roubles, is a venerable idea, but is not in
| widespread use in actual programming languages. Why not?
There was a pointer to some good papers on this in a
Ashley Yakeley after Tom Pledger:
The main complication is that the type system needs to deal with
integer exponents of dimensions, if it's to do the job well.
Very occasionally non-integer or 'fractal' exponents of dimensions are
useful. For instance, geographic coastlines can be
[EMAIL PROTECTED] (Marcin 'Qrczak' Kowalczyk) writes:
Why do you stop at allowing addition on Dollars and not include
multiplication by a scalar?
Perhaps because there is no good universal type for (*).
Sorry, it would have to have a different symbol.
Is this ubiquitous enough that we
On 12 Feb 2001, Ketil Malde wrote:
[EMAIL PROTECTED] (Marcin 'Qrczak' Kowalczyk) writes:
Why do you stop at allowing addition on Dollars and not include
multiplication by a scalar?
Perhaps because there is no good universal type for (*).
Sorry, it would have to have a different
On Mon, 12 Feb 2001, Ashley Yakeley wrote:
class (Additive a) = Scalable a
scale :: Real - a - a -- equivalent to * (not sure of name for Real type)
Or times, which would require multiparameter classes.
5 `times` "--" == "--"
5 `times` (\x - x+1) === (\x - x+5)
But this
In a later posting Marcin Kowalczyk says:
If (+) can be implicitly lifted to functions, then why not signum?
Note that I would lift neither signum nor (+). I don't feel the need.
...
On Mon, Feb 12, 2001 at 09:33:03AM +, Jerzy Karczmarczuk wrote:
I not only feel the need, but I feel
On Mon, 12 Feb 2001, Jerzy Karczmarczuk wrote:
I not only feel the need, but I feel that this is important that the
additive structure in the codomain is inherited by functions.
It could support only the basic arithmetic. It would not automatically
lift an expression which uses () and if. It
On Mon, 12 Feb 2001, Jerzy Karczmarczuk wrote:
I want to be *able* to define mathematical operations upon objects
which by their intrinsic nature permit so!
You can't do it in Haskell as it stands now, no matter what the Prelude
would be.
For example I would say that with the definition
Mon, 12 Feb 2001 12:04:39 +0100 (CET), Marcin 'Qrczak' Kowalczyk
[EMAIL PROTECTED] pisze:
This is my bet.
I changed my mind:
class Eq a = PartialOrd a where -- or Ord
(), (), (=), (=) :: a - a - Bool
-- Minimal definition: () or (=).
-- For partial order (=) is
Marcin Kowalczyk continues:
On Mon, 12 Feb 2001, Jerzy Karczmarczuk wrote:
I want to be *able* to define mathematical operations upon objects
which by their intrinsic nature permit so!
You can't do it in Haskell as it stands now, no matter what the Prelude
would be.
For example I
On Mon, Feb 12, 2001 at 04:40:06PM +, Jerzy Karczmarczuk wrote:
This is the way I program in Clean, where there is no Num, and (+), (*),
zero, abs, etc. constitute classes by themselves. ...
I've heard Clean mentioned before in this context, but I haven't found
the Clean numeric class
On Mon, Feb 12, 2001 at 07:24:31AM +, Marcin 'Qrczak' Kowalczyk wrote:
Sun, 11 Feb 2001 22:27:53 -0500, Dylan Thurston [EMAIL PROTECTED] pisze:
Reading this, it occurred to me that you could explictly declare an
instance of Powerful Integer Integer and have everything else work.
No,
On Sun, Feb 11, 2001 at 09:17:53PM -0800, William Lee Irwin III wrote:
Consider taking of the residue of a truly infinite member of Z[[x]]
mod an ideal generated by a polynomial, e.g. 1/(1-x) mod (1+x^2).
You can take the residue of each term of 1/(1-x), so x^(2n) - (-1)^n
and x^(2n+1) -
[incomprehensible (not necessarily wrong!) stuff about polynomials,
rings, modules over Z and complaints about the current prelude nuked]
--- Marcin 'Qrczak' Kowalczyk pisze ---
Please show a concrete proposal how Prelude classes could be improved.
--- Jerzy Karczmarczuk repondre ---
I am
| I'm seeing a bit of this now, and the error messages GHC spits out
| are hilarious! e.g.
|
| My brain just exploded.
| I can't handle pattern bindings for
| existentially-quantified constructors.
|
| and
|
| Couldn't match `Bool' against `Bool'
| Expected type: Bool
|
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