RecordUS is stored as a HList of RecordU to allow the RecordUS to contain elements of different types, so long all of the types can be put into an unboxed array (UArray).

It is advantageous (at least space-wise) to sort the record to keep elements with the same types elements adjacent. See SortForRecordUS for more details.

connect the unpacked x representation with the corresponding list of RecordU u representation.

proof that hMap UnboxF :: r xs -> r us can determine xs from us and us from xs

A type which behaves similarly to Record, except all elements must fit in the same UArray. A consequence of this is that RecordU has the following properties:

• it is strict in the element types
• it cannot do type-changing updates of RecordU, except if the function applies to all elements
• it probably is slower to update the very first elements of the RecordU

The benefit is that lookups should be faster and records should take up less space. However benchmarks done with a slow HNat2Integral do not suggest that RecordU is faster than Record.

Reorders a Record such that the RecordUS made from it takes up less space

Bad has alternating Double and Int fields

>>> bad
Record{x=1.0,i=2,y=3.0,j=4}

4 arrays containing one element each are needed when this Record is stored as a RecordUS

>>> recordToRecordUS bad
RecordUS H[RecordU (array (0,0) [(0,1.0)]),RecordU (array (0,0) [(0,2)]),RecordU (array (0,0) [(0,3.0)]),RecordU (array (0,0) [(0,4)])]

It is possible to sort the record

>>> sortForRecordUS bad
Record{x=1.0,y=3.0,i=2,j=4}

This allows the same content to be stored in two unboxed arrays

>>> recordToRecordUS (sortForRecordUS bad)
RecordUS H[RecordU (array (0,1) [(0,1.0),(1,3.0)]),RecordU (array (0,1) [(0,2),(1,4)])]

HSubtract a b is Left (a-b), Right (b-a) or Right HZero

Iso (HList s) (HList t) (RecordUS a) (RecordUS b)

Iso (HList s) (RecordUS a)

s is a HList of RecordU while a :: [*] is list of Tagged label value

view unboxedS or ^. unboxedS are preferred

^. from unboxedS is preferred

Iso (Record x) (Record y) (RecordUS x) (RecordUS y)

Iso' (Record x) (RecordUS x)

all elements of the list have the same type

analogous flip //. Similar to .<++., except it is restricted to cases where the left argument holds a subset of elements.

behaves like map HFind

hMap specialized to RecordU

Iso (Record x) (Record y) (RecordU x) (RecordU y)

Iso' (Record x) (RecordU x)

HasField instances

RecordUS

>>> let r = recordToRecordUS (sortForRecordUS bad)
>>> let s = recordToRecordUS bad

>>> let x = Label :: Label "x"
>>> let y = Label :: Label "y"
>>> let i = Label :: Label "i"
>>> let j = Label :: Label "j"

>>> (r .!. x, r .!. i, r .!. y, r .!. j)
(1.0,2,3.0,4)

>>> (s .!. x, s .!. i, s .!. y, s .!. j)
(1.0,2,3.0,4)

RecordU

>>> let t = recordToRecordU bad1
>>> (t .!. x, t .!. y)
(1.0,2.0)

>>> hUpdateAtLabel x 3 t .!. x
3.0