「Java 8を関数型っぽく使うためのおまじないをGroovyでやってみた」をGroovyにした

バイク川崎バイク.groovy

String.metaClass.define {
    enclose = {
        "[${delegate}]" as String
    }
}

assert '[foo]' == 'foo'.enclose()

assert 'Foo' == 'foo'.capitalize()

assert '[Foo]' == 'foo'.capitalize().enclose()

String.metaClass.define {
    middle = {
        delegate.substring(delegate.size() / 3 as int, delegate.size() * 2 / 3 as int)
    }
}

assert 'foo' == 'fizfoobar'.middle()
assert '[Foo]' == 'fizfoobar'.middle().capitalize().enclose()

String.metaClass.define {
    sandwich = {enc ->
        "${enc}${delegate}${enc}" as String
    }
}

assert 'バイク川崎バイク' == '川崎'.sandwich('バイク')

/* 
 * カリー化 != 部分適用
 */

String.metaClass.define {
    haskell = {pre ->
        def item = delegate
        return {post -> "$pre$item$post" as String}
    }
    haskell = {pre, post ->
        "$pre$delegate$post" as String
    }
}

assert 'ばいく川崎バイク' == '川崎'.haskell('ばいく')('バイク')
assert 'ばいく川崎バイク' == '川崎'.haskell('ばいく', 'バイク')