Elm tuples with more than three values

People often run into the tuple size limit of 3 and wonder why Elm doesn't allow 4+, especially if you're coming from Haskell.

In Elm, we use a record instead.

Comparison

Here are some before/after refactoring examples in moving from a Tuple with 3 fields (a Triple) to a record with 4 fields.

Changing the type definition

type alias Coords = ( Int, Int, Int )
type alias Coords = { x: Int, y: Int, z: Int, q: Int }

The main change is we now explicitly label the values, and

()

changed to

{}

Creating a value

Creating a value is not much different:

myCoord = ( x, y, z )
myCoord = Coords x y z q

Instead of

( .. , .. , ..)

we use

RecordAliasName .. .. .. ..

De-structuring a value

Using Record de-structuring is almost the same as Tuple de-structuring:

someFn ( x, y, z ) = ...
someFn { x, y, z, q } = ...

The main difference is now

x/y/z/q

must be used (as they are the specified names).

someFn ( x1, y1, z1 ) ( x2, y2, z2 ) =
  (x1 + x2, y1 + y2, z1 + z2)

someFn c1 c2 =                                         -- minus 24 chars
  (c1.x + c2.x, c1.y + c2.y, c1.z + c2.z, c1.q + c1.q) -- plus  25 chars

The record version ends up with 1 char more than the tuple version... but we added another field!