With GHC-5.02.2, I do
$ ghci
Prelude :m Ratio
Ratio [1%2..10%2]
[1 % 2,3 % 2,5 % 2,7 % 2,9 % 2,11 % 2]
The question is, why is there 11%2 at the end of the list?
It's inconsistent with the (good) rules for Integer, since
Ratio [1,3..10]
[1,3,5,7,9]
Is this intentional?
Ferenc Wagner [EMAIL PROTECTED] writes:
$ ghci
Prelude :m Ratio
Ratio [1%2..10%2]
[1 % 2,3 % 2,5 % 2,7 % 2,9 % 2,11 % 2]
H, the CVS copy of Hugs seems to suffer from a different problem:
Prelude [0.5,1.5..5.5]::[Rational]
[0 % 1,1 % 1,2 % 1,3 % 1,4 % 1,5 % 1]
I'm expecting to see:
[1 %
Alastair Reid:
Ferenc Wagner [EMAIL PROTECTED] writes:
H, the CVS copy of Hugs seems to suffer from a different problem:
Prelude [0.5,1.5..5.5]::[Rational]
[0 % 1,1 % 1,2 % 1,3 % 1,4 % 1,5 % 1]
I'm expecting to see:
[1 % 2,3 % 2,5 % 2,7 % 2,9 % 2,11 % 2]
Rationals in Hugs were
The Report says that the Enum instance for Ratio uses the same rule as
for Float/Double, namely that
[a..b]
means
takeWhile (= (b+1/2)) [a, a+1, a+2, ...]
You may say that the = should be but that's what the Report says.
Certainly if you do [1%3..10%3] you'll get more values
Simon Peyton-Jones [EMAIL PROTECTED] writes:
The Report says that the Enum instance for Ratio uses the
same rule as for Float/Double,
Now I can see that the revised Report contains more about
this than the one on haskell.org. But I still can't see the
statement you cited above. Where should
Jerzy Karczmarczuk [EMAIL PROTECTED] writes:
Rationals in Hugs were always a bit obscure. What do you think, what
is the Rational form of 2.3 ? (GHCi says 23/10).
The answer is:
2589569785738035 % 1125899906842624
(Old Hugs, Feb. 2001)
I'm afraid the new release won't fix this.
Once
Jerzy Karczmarczuk wrote (on 22-10-02 13:05 +0200):
What do you think, what
is the Rational form of 2.3 ? (GHCi says 23/10).
The answer is:
2589569785738035 % 1125899906842624
Er, why?
Because 2.3 is not representable using a double precision float or something?
--
Frank
Thanks for your reply...
Paul Hudak [EMAIL PROTECTED] writes:
case expr of
C f - ...
V (Variable (VVariable s)) - ...
...
I think you mean:
case expr of
C f - ...
V (VVariable s) - ...
which is not quite as verbose.
Yes, I think I should have checked my
(I'm not sure why my postings seem somewhat anonymous, I'll mess with
the headers in this post to see if that fixes it. I post to other
mailman lists and haven't noticed this problem.)
I'm working through Paul Hudak's SOE, and have a question about
problem 9.4, which is to define a function
applyEach [(+1), (+3), (+2)] 1
= [2,4,3] :: [Integer]
applyEach' :: [a-b] - a - [b]
applyEach' funs x = map applyx funs where applyx (fun) = fun x
...or more simply:
applyEach' l x = map ($x) l
___
Haskell-Cafe mailing list
[EMAIL PROTECTED]
Frank Atanassow wrote (on 22-10-02 15:08 +0200):
Jerzy Karczmarczuk wrote (on 22-10-02 13:05 +0200):
What do you think, what
is the Rational form of 2.3 ? (GHCi says 23/10).
The answer is:
2589569785738035 % 1125899906842624
Er, why?
Because 2.3 is not representable using a
Tim Otten writes:
:
| Can anyone suggest why the tighter algorithm exhibits significantly
| worse performance? Is takeWhile significicantly more expensive than
| take?
No.
| Is the \z lambda expression expensive?
No.
| The intsqrt isn't recalculated each time takeWhile evalutes a
|
Tom Pledger writes:
| Tim Otten writes:
| :
| | Can anyone suggest why the tighter algorithm exhibits significantly
| | worse performance? Is takeWhile significicantly more expensive than
| | take?
|
| No.
Correction (before anyone else pounces on it):
Only if the predicate function
Variable (VVariable(varName, (Value (Number
(NNumber (varValue, varDimension))
Here VVariable and NNumber are newtype constructors of tuples, and the
entire expression is an Expression which, among other things has:
data Expression =
Value
G'day all.
On Thu, Oct 17, 2002 at 11:08:57AM -0400, [EMAIL PROTECTED] wrote:
For an
interpreter I'm writing, I found myself writing a function
constructVarExpr :: String - Expr just to make it easier.
As an alternative opinion, I don't think there's anything wrong
with this. A constructor
Hi All
I don't know what I'm doing wrong here but for some
reason no matter what esoteric command line option I seem to be able to dream up
I can get ghc to include IOExts..I want to use the side-affect IO commands but
cannot.
I am using ghc-5.02.2for Win32.
Can someone just give me a
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