singularize ( word -- singular )
English natural language transformations

Prev:	singular? ( word -- ? )
Next:	a/an ( word -- article )

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
$keep-case

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 ;