singularize ( word -- singular )
English natural language transformations

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Vocabulary
english

Inputs

word

a string

Outputs

singular

a string

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

Notes
This word attempts to preserve the letter case style of the input.

Examples

USING: english io ; "CATS" singularize print
CAT

USING: english io ; "Octopi" singularize print
Octopus

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

Definition

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

IN: english

: singularize ( word -- singular )
    dup >lower {
        { [ dup empty? ] [ ] }
        { [ dup singular-to-plural key? ] [ ] }
        { [ plural-to-singular ?at ] [ ] }
        { [ dup "s" tail? not ] [ ] }
        {
            [
                dup "ies" ?tail
                [ last vowel? not ] [ drop f ] if
            ]
            [ 3 head* "y" append ]
        }
        { [ dup "es" tail? ] [ 2 head* ] }
        [ but-last ]
    } cond match-case ;