Some more questions about types. I just ran into the recursive 'type alias' 

which is clear enough. It seems a bit of a shame that some of this 
documentation is a bit buried away - it really feels like this should be in 
the syntax guide (or whatever chapter comes after the syntax guide). 
Anyway, the other questions:

Can type definitions be recursive? as per ML, I think the answer is yes.

type Expression
  = Integer Int
  | Sum Expression Expression

for a simple syntax tree representing expressions over integers and 

I have seen some type definitions like this:

type Cmd msg = Cmd

but I am more used to seeing type definitions that look like this:

type Msg
  = SomeMsg String
  | ...

What does the 'msg' parameter on this type do? Does it just mean that the 
type is polymorphic and the 'msg' is the type parameter? So the definition 
of List might look like:

type List a
 = Nil
 | Cons a (List a)

You received this message because you are subscribed to the Google Groups "Elm 
Discuss" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
For more options, visit

Reply via email to