FQL function to convert the result of an index with values, to an object with the field names

function.js

CreateFunction({
	name: 'GetIndexValuesObject',
	body: Query(
		Lambda(
			['indexRef', 'indexValuesArray'],
			Let(
				{
					keys: Let(
						{
							indexDoc: Get(Var('indexRef')),
							indexValues: Select('values', Var('indexDoc'))
						},
						Map(
							Var('indexValues'),
							Lambda(
								'fieldObj',
								Let(
									{
										array: Select('field', Var('fieldObj')),
										length: Count(Var('array')),
										lastIndex: Subtract(Var('length'), 1)
									},
									Select(Var('lastIndex'), Var('array'))
								)
							)
						)
					),
					keysWithIndexes: Reduce(
						Lambda(
							['accumulator', 'value'],
							Append([[Var('value'), Count(Var('accumulator'))]], Var('accumulator'))
						),
						[],
						Var('keys')
					)
				},
				Map(
					Var('indexValuesArray'),
					Lambda(
						'values',
						ToObject(
							Map(
								Var('keysWithIndexes'),
								Lambda(
									'keyWithIndex',
									Let(
										{
											key: Select(0, Var('keyWithIndex')),
											index: Select(1, Var('keyWithIndex')),
											value: Select(Var('index'), Var('values'), null)
										},
										[Var('key'), Var('value')]
									)
								)
							)
						)
					)
				)
			)
		)
	)
})

test.js

Let(
	{
		indexRef: Index("Index_with_values"),
		values: Select(
			"data",
			Paginate(Match(Var('indexRef')))
		)
	},
	Call(Function("GetIndexValuesObject"), [
		Var('indexRef'),
		Var('values')
	])
)