What does comparable mean in Elm?

Question

I\'m having trouble understanding what exactly a comparable is in Elm. Elm seems as confused as I am.

On the REPL:

> f1 = (<)
&l         


        

Answer 1

UPDATE: thanks to @charlie inputs i include this:

Compare any two comparable values. Comparable values include String, Char, Int, Float, Time, or a list or tuple containing comparable values. These are also the only values that work as Dict keys or Set members.

taken from the elm docs: - here

Older version:

Comparable types includes numbers, characters, strings,~~ lists of comparable things, and tuples of comparable things. Note that tuples with 7 or more elements are not comparable; why are your tuples so big?

This means that:

[(1,"string"), (2, "another string")] : List (Int, String) - is comparable

But having

(1, "string", True) : (Int, String, Bool) or

[(1,True), (2, False)] : List (Int, Bool ) - are not comparable yet.

This issue is discussed here

Note: Usually people encounter problems with the comparable type when they try to use a union type as a Key in a Dict.

Tags and Constructors of union types are not comparable. So the following doesn't even compile.

type SomeUnion = One | Two | Three
Dict.fromList [ (One, "one related"), (Two, "two related") ] : Dict SomeUnion String

Usually when you try to do this, there is a better approach to your data structure. But until this gets decided - an AllDict can be used.