Re: [Haskell-beginners] import question

Like others said, you'll need to install the Decimal package in order to use Data.Decimal. If you really wanted to do it with a floating point type and no dependencies you can use showFFloatAlt from Numeric to display with a specified precision. import Numeric import Text.Show main = putStrLn . showListWith (showFFloatAlt (Just 2)) [1.00, 1.01 .. 2.00] $ "" On Wed, Feb 17, 2021 at 7:42 PM Galaxy Being wrote:

As I've said, working at the ghci REPL,

import Data.Decimal dList :: [Decimal] dList = [1.00,1.01..2.00] main = print dList

errors out

: <interactive>:76:11-17: error: : Not in scope: type constructor or class `Decimal'

On Wed, Feb 17, 2021 at 8:37 PM Bob Ippolito wrote:

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You don't need to do any rounding if the list is already Decimal.

If you wanted to format a Double with some specific decimal representation you could look at Numeric.showFFloatAlt or similar.

import Data.Decimal

dList :: [Decimal] dList = [1.00,1.01..2.00]

main = print dList

On Wed, Feb 17, 2021 at 5:27 PM Galaxy Being wrote:

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I'm trying to create a list of real numbers with a two-decimal interval, a la

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[1.0,1.01,1.02,...1.99,2.00]

however, I get the float approximation problem

[1.0,1.01,1.02,1.03,1.04,1.05,1.06,1.07,1.08,1.09,1.1,1.11,1.12,1.1300000000000001,1.1400000000000001,...

So I attempted to compensate with

import Data.Decimal map (roundTo 2) [1.00,1.01..2.0]

I don't have to do it this way if there is another rounding function to correct the float overrun issue.

On Wed, Feb 17, 2021 at 2:43 PM Francesco Ariis wrote:

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How would I install it globally? I'm not using projects, I'm just at

Il 17 febbraio 2021 alle 14:17 Galaxy Being ha scritto: the

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ghci REPL.

Most likely

cabal install --lib Decimal

Check what Tom has said too —F _______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners

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