Filter unwanted attributes from an object

Attrs ["nice", "good"]

-- { bad: 3, good: 1, nice: 500, evil: -3 }
-- => { good: 1, nice: 500 }

Grab value

Attr "foo"

-- { foo: 2 } => 2

Dig deeper

At "foo" $ Attr "bar"

-- { foo: { bar: 3 }} => 3

Map stuff

Map $ Attr "foo"

-- [{ foo:1, foo:2 }] => [1, 2]

Extract indices

Map $ Index 0 Id

-- [[1,2], [3,4]] => [1, 3]

Create object

Obj $ fromList [
    ("first", Index 0 Id)
  , ("second", Index 1 Id)
  ]

-- ["hi", "bye"] => { first:"hi", second:"bye" }