Module `Standard.Char`

Functions for working with single characters.

type t = char

Create

You can create a Char using single quotes:

let char = 'c'

val ofCode : int -> char option

Convert an ASCII code point to a character.

Returns None if the codepoint is outside the range of 0 to 255 inclusive.

Examples

Char.ofCode 65 = Some 'A'

Char.ofCode 66 = Some 'B'

Char.ofCode 3000 = None

Char.ofCode (-1) = None

The full range of extended ASCII is from 0 to 255. For numbers outside that range, you get None.

val ofString : string -> char option

Converts a string to a character.

Returns None when the string isn't of length one.

Examples

Char.ofString "A" = Some 'A'

Char.ofString " " = Some ' '

Char.ofString "" = None

Char.ofString "abc" = None

Char.ofString " a" = None

Query

val isLowercase : char -> bool

Detect lower case ASCII characters.

Examples

Char.isLowercase 'a' = true

Char.isLowercase '0' = false

Char.isLowercase 'A' = false

Char.isLowercase '-' = false

val isUppercase : char -> bool

Detect upper case ASCII characters.

Examples

Char.isUppercase 'A' = true

Char.isUppercase 'h' = false

Char.isUppercase '0' = false

Char.isUppercase '-' = false

val isLetter : char -> bool

Detect upper and lower case ASCII alphabetic characters.

Examples

Char.isLetter 'a' = true

Char.isLetter 'E' = true

Char.isLetter '0' = false

Char.isLetter '-' = false

val isDigit : char -> bool

Detect when a character is a number

Examples

Char.isDigit '0' = true

Char.isDigit '9' = true

Char.isDigit 'a' = false

Char.isDigit '-' = false

val isAlphanumeric : char -> bool

Detect upper case, lower case and digit ASCII characters.

Examples

Char.isAlphanumeric 'a' = true

Char.isAlphanumeric 'E' = true

Char.isAlphanumeric '0' = true

Char.isAlphanumeric '-' = false

val isPrintable : char -> bool

Detect if a character is a printable character

A Printable character has a Char.toCode in the range 32 to 127, inclusive (' ' to '~').

Examples

Char.isPrintable 'G' = true

Char.isPrintable '%' = true

Char.isPrintable ' ' = true

Char.isPrintable '\t' = false

Char.isPrintable '\007' = false

val isWhitespace : char -> bool

Detect one of the following characters:

'\t' (tab)
'\n' (newline)
'\011' (vertical tab)
'\012' (form feed)
'\r' (carriage return)
' ' (space)

Examples

Char.isWhitespace '\t' = true

Char.isWhitespace ' ' = true

Char.isWhitespace '?' = false

Char.isWhitespace 'G' = false

Transform

val toLowercase : char -> char

Converts an ASCII character to lower case, preserving non alphabetic ASCII characters.

Examples

Char.toLowercase 'A' = 'a'

Char.toLowercase 'B' = 'b'

Char.toLowercase '7' = '7'

val toUppercase : char -> char

Convert an ASCII character to upper case, preserving non alphabetic ASCII characters.

Examples

toUppercase 'a' = 'A'

toUppercase 'b' = 'B'

toUppercase '7' = '7'

Convert

val toCode : char -> int

Convert to the corresponding ASCII code point.

Examples

Char.toCode 'A' = 65

Char.toCode 'B' = 66

val toString : char -> string

Convert a character into a string.

Examples

Char.toString 'A' = "A"

Char.toString '{' = "{"

Char.toString '7' = "7"

val toDigit : char -> int option

Converts a digit character to its corresponding Int.

Returns None when the character isn't a digit.

Examples

Char.toDigit "7" = Some 7

Char.toDigit "0" = Some 0

Char.toDigit "A" = None

Char.toDigit "" = None

Compare

val equal : char -> char -> bool

Test two Chars for equality

val compare : char -> char -> int

Compare two Chars

type identity

The unique identity for chars Comparator

val comparator : (char, identity) Standard__.Core.Comparator.t

package reason-standard

Module Standard.Char

Create

Query

Transform

Convert

Compare

Module `Standard.Char`