Foundation.String.Read

Documentation

readInteger :: String -> Maybe Integer

Read an Integer from a String

Consume an optional minus sign and many digits until end of string.

readNatural :: String -> Maybe Natural

Read a Natural from a String

Consume many digits until end of string.

readDouble :: String -> Maybe Double

Try to read a Double

readFloatingExact :: String -> ReadFloatingCallback a -> Maybe a

Read an Floating like number of the form:

-

numbers [ . numbers ] [ ( e | E ) [ - ] number ]

Call a function with:

• A boolean representing if the number is negative
• The leading integral part
• The floating part (number of digits after fractional part, and number) if any
• The exponant if any

The code is structured as a simple state machine that:

• Optionally Consume a - sign
• Consume number for the integral part
• Optionally
• Consume .
• Consume leading zeros explicitely to gather scale of the fractional part
• Consume remaining digits if not already end of string
• Optionally Consume a e or E follow by an optional - and a number