Data.Quantity

Tools for rendering sizes

Written by John Goerzen, [e-mail]

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.