A Char is a single unicode character:

'a'
'0'
'Z'
'?'
'"'
'Σ'
'🙈'


'\t'
'\"'
'\''
'\u{1F648}' -- '🙈'

Note 1: You cannot use single quotes around multiple characters like in JavaScript. This is how we distinguish String and Char values in syntax.

Note 2: You can use the unicode escapes from \u{0000} to \u{10FFFF} to represent characters by their code point. You can also include the unicode characters directly. Using the escapes can be better if you need one of the many whitespace characters with different widths.

Detect upper case ASCII characters.

isUpper 'A' == True
isUpper 'B' == True
...
isUpper 'Z' == True


isUpper '0' == False
isUpper 'a' == False
isUpper '-' == False
isUpper 'Σ' == False

Detect lower case ASCII characters.

isLower 'a' == True
isLower 'b' == True
...
isLower 'z' == True


isLower '0' == False
isLower 'A' == False
isLower '-' == False
isLower 'π' == False

Detect upper case and lower case ASCII characters.

isAlpha 'a' == True
isAlpha 'b' == True
isAlpha 'E' == True
isAlpha 'Y' == True


isAlpha '0' == False
isAlpha '-' == False
isAlpha 'π' == False

Detect upper case and lower case ASCII characters.

isAlphaNum 'a' == True
isAlphaNum 'b' == True
isAlphaNum 'E' == True
isAlphaNum 'Y' == True
isAlphaNum '0' == True
isAlphaNum '7' == True


isAlphaNum '-' == False
isAlphaNum 'π' == False

Detect digits 0123456789

isDigit '0' == True
isDigit '1' == True
...
isDigit '9' == True


isDigit 'a' == False
isDigit 'b' == False
isDigit 'A' == False

Detect octal digits 01234567

isOctDigit '0' == True
isOctDigit '1' == True
...
isOctDigit '7' == True


isOctDigit '8' == False
isOctDigit 'a' == False
isOctDigit 'A' == False

Detect hexadecimal digits 0123456789abcdefABCDEF

Convert to upper case.

Convert to lower case.

Convert to upper case, according to any locale-specific case mappings.

Convert to lower case, according to any locale-specific case mappings.

Convert to the corresponding Unicode code point.

toCode 'A' == 65 toCode 'B' == 66 toCode '木' == 0x6728 toCode '𝌆' == 0x1D306 toCode '😃' == 0x1F603

Convert a Unicode code point to a character.

fromCode 65      == 'A'
fromCode 66      == 'B'
fromCode 0x6728  == '木'
fromCode 0x1D306 == '𝌆'
fromCode 0x1F603 == '😃'
fromCode -1      == '�'

The full range of unicode is from 0 to 0x10FFFF. With numbers outside that range, you get the replacement character.