pluralize ( word -- plural )
English natural language transformations

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Next:	?pluralize ( count singular -- singular/plural )

Vocabulary
english

Inputs

word

a string

Outputs

plural

a string

Word description
Determine the plural form of the input English word. If the input is already plural, it might be returned unchanged.

Notes

•	If the input is already in plural form, an invalid construct such as friendses may be generated. This is difficult to avoid due to the unpredictable structure of the English language.
•	This word attempts to preserve the letter case style of the input.

Examples

USING: english io ; "CAT" pluralize print
CATS

USING: english io ; "Octopus" pluralize print
Octopi

See also
?pluralize, plural?, count-of-things, singularize, singular?

Definition

USING: assocs combinators english.private kernel sequences
splitting unicode ;

IN: english

: pluralize ( word -- plural )
    dup >lower {
        { [ dup empty? ] [ ] }
        { [ dup plural-to-singular key? ] [ ] }
        { [ singular-to-plural ?at ] [ ] }
        {
            [ dup "y" ?tail [ last vowel? not ] [ drop f ] if ]
            [ but-last "ies" append ]
        }
        {
            [ dup { "s" "ch" "sh" } [ tail? ] with any? ]
            [ dup "es" tail? [ "es" append ] unless ]
        }
        [ "s" append ]
    } cond match-case ;