Returns True for lower-case characters.

It uses the character property Lowercase.

See: isLower for the legacy predicate.

Since: 0.3.0

Returns True for upper-case characters.

It uses the character property Uppercase.

Note: it does not match title-cased letters. Those are matched using: generalCategory c == TitlecaseLetter.

See: isUpper for the legacy predicate.

Since: 0.3.0

Returns the full folded case mapping of a character if the character is changed, else nothing.

It uses the character property Case_Folding.

Since: 0.3.1

Convert a character to full folded case if defined, else to itself.

This function is mainly useful for performing caseless (also known as case insensitive) string comparisons.

A string x is a caseless match for a string y if and only if:

foldMap toCaseFoldString x == foldMap toCaseFoldString y

The result string may have more than one character, and may differ from applying toLowerString to the input string. For instance, “ﬓ” (U+FB13 Armenian small ligature men now) is case folded to the sequence “մ” (U+0574 Armenian small letter men) followed by “ն” (U+0576 Armenian small letter now), while “µ” (U+00B5 micro sign) is case folded to “μ” (U+03BC Greek small letter mu) instead of itself.

It uses the character property Case_Folding.

toCaseFoldString c == foldMap toCaseFoldString (toCaseFoldString c)

Since: 0.3.1

Returns the full lower case mapping of a character if the character is changed, else nothing.

It uses the character property Lowercase_Mapping.

Since: 0.3.1

Convert a character to full lower case if defined, else to itself.

The result string may have more than one character. For instance, “İ” (U+0130 Latin capital letter I with dot above) maps to the sequence: “i” (U+0069 Latin small letter I) followed by “ ̇” (U+0307 combining dot above).

It uses the character property Lowercase_Mapping.

See: toLower for simple lower case conversion.

toLowerString c == foldMap toLowerString (toLowerString c)

Since: 0.3.1

Returns the full title case mapping of a character if the character is changed, else nothing.

It uses the character property Titlecase_Mapping.

Since: 0.3.1

Convert a character to full title case if defined, else to itself.

The result string may have more than one character. For instance, “fl” (U+FB02 Latin small ligature FL) is converted to the sequence: “F” (U+0046 Latin capital letter F) followed by “l” (U+006C Latin small letter L).

It uses the character property Titlecase_Mapping.

See: toTitle for simple title case conversion.

Since: 0.3.1

Returns the full upper case mapping of a character if the character is changed, else nothing.

It uses the character property Uppercase_Mapping.

Since: 0.3.1

Convert a character to full upper case if defined, else to itself.

The result string may have more than one character. For instance, the German “ß” (U+00DF Eszett) maps to the two-letter sequence “SS”.

It uses the character property Uppercase_Mapping.

See: toUpper for simple upper case conversion.

toUpperString c == foldMap toUpperString (toUpperString c)

Since: 0.3.1

An Unfold a b is a generator of a stream of values of type b from a seed of type a.

Since: 0.3.1

A stream is a succession of Steps.

Since: 0.3.1