Char

The Char type represents a single Unicode character (code point). Characters are enclosed in single quotes and support Unicode.

Literals

Character Literal

Char

Character literals are enclosed in single quotes.

letter = 'a'
digit = '5'
emoji = '🦊'

println letter
# => 'a'

Conversions

Char.from-code-point

Int -> Option Char

Creates a character from a Unicode code point. Returns None for invalid code points.

println (Char.from-code-point 65)
# => Some('A')

println (Char.from-code-point 128054)
# => Some('🐶')

println (Char.from-code-point -1)
# => None

Char.to-code-point

Char -> Int

Returns the Unicode code point of a character.

println (Char.to-code-point 'A')
# => 65

println (Char.to-code-point '🐶')
# => 128054

Char.from-string

String -> Option Char

Converts a single-character string to a Char. Returns None if the string is empty or has multiple characters.

println (Char.from-string "a")
# => Some('a')

println (Char.from-string "ab")
# => None

println (Char.from-string "")
# => None

Char.to-string

Char -> String

Converts a character to a single-character string.

println (Char.to-string 'a')
# => "a"

println (Char.to-string '🦊')
# => "🦊"

Predicates

Char.is-alpha?

Char -> Bool

Returns true if the character is an alphabetic letter (a-z, A-Z).

println (Char.is-alpha? 'a')    # => true
println (Char.is-alpha? 'Z')    # => true
println (Char.is-alpha? '5')    # => false

Char.is-digit?

Char -> Bool

Returns true if the character is a decimal digit (0-9).

println (Char.is-digit? '5')    # => true
println (Char.is-digit? 'a')    # => false

Char.is-alphanumeric?

Char -> Bool

Returns true if the character is alphabetic or a digit.

println (Char.is-alphanumeric? 'a')    # => true
println (Char.is-alphanumeric? '5')    # => true
println (Char.is-alphanumeric? '!')    # => false

Char.is-whitespace?

Char -> Bool

Returns true if the character is whitespace (space, tab, newline, etc.).

println (Char.is-whitespace? ' ')     # => true
println (Char.is-whitespace? '\n')    # => true
println (Char.is-whitespace? 'a')     # => false

Char.is-uppercase?

Char -> Bool

Returns true if the character is an uppercase letter.

println (Char.is-uppercase? 'A')    # => true
println (Char.is-uppercase? 'a')    # => false

Char.is-lowercase?

Char -> Bool

Returns true if the character is a lowercase letter.

println (Char.is-lowercase? 'a')    # => true
println (Char.is-lowercase? 'A')    # => false

Char.is-ascii?

Char -> Bool

Returns true if the character is in the ASCII range (0-127).

println (Char.is-ascii? 'a')    # => true
println (Char.is-ascii? '🦊')   # => false

Char.is-control?

Char -> Bool

Returns true if the character is a control character.

println (Char.is-control? '\n')    # => true
println (Char.is-control? 'a')     # => false

Char.is-punctuation?

Char -> Bool

Returns true if the character is a punctuation character.

println (Char.is-punctuation? '.')    # => true
println (Char.is-punctuation? '!')    # => true
println (Char.is-punctuation? 'a')    # => false

Char.is-hex-digit?

Char -> Bool

Returns true if the character is a hexadecimal digit (0-9, a-f, A-F).

println (Char.is-hex-digit? 'a')    # => true
println (Char.is-hex-digit? 'F')    # => true
println (Char.is-hex-digit? 'g')    # => false

Char.is-printable?

Char -> Bool

Returns true if the character is printable (visible when rendered).

println (Char.is-printable? 'a')     # => true
println (Char.is-printable? ' ')     # => true
println (Char.is-printable? '\n')    # => false

Case Conversion

Char.to-uppercase

Char -> Char

Converts a character to uppercase. Non-letter characters are returned unchanged.

println (Char.to-uppercase 'a')    # => 'A'
println (Char.to-uppercase 'A')    # => 'A'
println (Char.to-uppercase '5')    # => '5'

Char.to-lowercase

Char -> Char

Converts a character to lowercase. Non-letter characters are returned unchanged.

println (Char.to-lowercase 'A')    # => 'a'
println (Char.to-lowercase 'a')    # => 'a'
println (Char.to-lowercase '5')    # => '5'

Comparison

Char.compare

Char -> Char -> Int

Compares two characters by their code points. Returns -1 if less, 0 if equal, 1 if greater.

println (Char.compare 'a' 'b')    # => -1
println (Char.compare 'b' 'b')    # => 0
println (Char.compare 'c' 'a')    # => 1

Working with Strings

Use String.chars to convert a string to a list of characters, and String.from-chars to convert back.

chars = String.chars "hello"
# => ['h', 'e', 'l', 'l', 'o']

upper = chars |> map Char.to-uppercase |> String.from-chars
# => "HELLO"