Data.Quantity

MissingH-1.1.1.0: Large utility library

Portability | portable
Stability | provisional
Maintainer | John Goerzen <jgoerzen@complete.org>

Data.Quantity

Description

Tools for rendering sizes

Written by John Goerzen, jgoerzen@complete.org

Synopsis

- renderNum :: (Ord a, Real a) => SizeOpts -> Int -> a -> String
- renderNums :: (Ord a, Real a) => SizeOpts -> Int -> [a] -> [String]
- parseNum :: (Read a, Fractional a) => SizeOpts -> Bool -> String -> Either String a
- parseNumInt :: (Read a, Integral a) => SizeOpts -> Bool -> String -> Either String a
- quantifyNum :: (Ord a, Real a, Floating b, Ord b) => SizeOpts -> a -> (b, Char)
- quantifyNums :: (Ord a, Real a, Floating b, Ord b) => SizeOpts -> [a] -> ([b], Char)
- data SizeOpts = SizeOpts {
  - base :: Int
  - powerIncr :: Int
  - firstPower :: Int
  - suffixes :: String
  }
- binaryOpts :: SizeOpts
- siOpts :: SizeOpts

# Documentation

renderNum

Arguments

:: (Ord a, Real a) |
=> SizeOpts |
-> Int | Precision of the result
-> a | The number to examine
-> String |

Render a number into a string, based on the given quantities. This is useful for displaying quantities in terms of bytes or in SI units. Give this function the `SizeOpts` for the desired output, and a precision (number of digits to the right of the decimal point), and you get a string output.

Here are some examples:

     Data.Quantity> renderNum binaryOpts 0 1048576
     "1M"
     Data.Quantity> renderNum binaryOpts 2 10485760
     "10.00M"
     Data.Quantity> renderNum binaryOpts 3 1048576
     "1.000M"
     Data.Quantity> renderNum binaryOpts 3 1500000
     "1.431M"
     Data.Quantity> renderNum binaryOpts 2 (1500 ** 3)
     "3.14G"

     Data.Quantity> renderNum siOpts 2 1024
     "1.02k"
     Data.Quantity> renderNum siOpts 2 1048576
     "1.05M"
     Data.Quantity> renderNum siOpts 2 0.001
     "1.00m"
     Data.Quantity> renderNum siOpts 2 0.0001
     "100.00u"

If you want more control over the output, see `quantifyNum`.

renderNums

Arguments

:: (Ord a, Real a) |
=> SizeOpts |
-> Int | Prevision of the result
-> [a] | The numbers to examine
-> [String] | Result

Like `renderNum`, but operates on a list of numbers. The first number in the list will be evaluated for the suffix. The same suffix and scale will be used for the remaining items in the list. See `renderNum` for more examples.

Also, unlike `renderNum`, the %f instead of %g printf format is used so that "scientific" notation is avoided in the output.

Examples:

     *Data.Quantity> renderNums binaryOpts 3 [1500000, 10240, 104857600]
     ["1.431M","0.010M","100.000M"]
     *Data.Quantity> renderNums binaryOpts 3 [1500, 10240, 104857600]
     ["1.465K","10.000K","102400.000K"]

parseNum

Arguments

:: (Read a, Fractional a) |
=> SizeOpts | Information on how to parse this data
-> Bool | Whether to perform a case-insensitive match
-> String | The string to parse
-> Either String a |

Parses a String, possibly generated by `renderNum`. Parses the suffix and applies it to the number, which is read via the Read class.

Returns Left error message on error, or Right number on successful parse.

If you want an Integral result, the convenience function `parseNumInt` is for you.

parseNumInt

Arguments

:: (Read a, Integral a) |
=> SizeOpts | Information on how to parse this data
-> Bool | Whether to perform a case-insensitive match
-> String | The string to parse
-> Either String a |

Parse a number as with `parseNum`, but return the result as an `Integral`. Any type such as Integer, Int, etc. can be used for the result type.

This function simply calls `round` on the result of `parseNum`. A `Double` is used internally for the parsing of the numeric component.

By using this function, a user can still say something like 1.5M and get an integral result.

quantifyNum :: (Ord a, Real a, Floating b, Ord b) => SizeOpts -> a -> (b, Char)

Takes a number and returns a new (quantity, suffix) combination. The space character is used as the suffix for items around 0.

quantifyNums :: (Ord a, Real a, Floating b, Ord b) => SizeOpts -> [a] -> ([b], Char)

Like `quantifyNum`, but takes a list of numbers. The first number in the list will be evaluated for the suffix. The same suffix and scale will be used for the remaining items in the list. Please see `renderNums` for an example of how this works.

It is invalid to use this function on an empty list.

data SizeOpts

The options for `quantifyNum` and `renderNum`

Constructors

SizeOpts |
Fields base :: Int The base from which calculations are made powerIncr :: Int The increment to the power for each new suffix firstPower :: Int The first power for which suffixes are given suffixes :: String The suffixes themselves

binaryOpts :: SizeOpts

Predefined definitions for byte measurement in groups of 1024, from 0 to 2**80

siOpts :: SizeOpts

Predefined definitions for SI measurement, from 10**-24 to 10**24.