[elm-discuss] New to Elm, need help understanding type Node msg = Node in source code

[Will Tian]

Hi,

I'm trying to understand how the Html module works. I see many methods with 
return type Html msg, which is a type alias for Node msg. 

After tracking down the source code and reading into it, I am confused by 
the following line: 

type Node msg = Node

what is the purpose of the above line? 

Furthermore, I don't understand the use of the type parameter msg.

For example I can see that type Property msg = Property

and 

property : String -> Json.Value -> Property msg
property = Native.VirtualDom.property

when looking into the implementation of VirtualDom.property, I see 

function property(key, value)
{
return {
key: key,
value: value
};
}

Does that mean the return value of calling: property "className" 
(Json.string "myClass") is of type Property msg where msg = { key: 
"className", value: "myClass" }?
does the property function actually use a type constructor and return the 
type?

Thanks in advance.


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Re: [elm-discuss] Starting Elm, need help understanding -> syntax

[Will Tian]

Yep, that makes perfect sense. I did not realize that in Elm all functions 
take exactly one argument and return a result

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[elm-discuss] Starting Elm, need help understanding -> syntax

[Will Tian]

Hi,

I am having trouble understanding the -> syntax in elm. 

For example 

if we have the function:

plusTwo x = x + 2

it's type definition will be as follows: 
 : number -> number

this is pretty straight forward

however, if we have the function

add x y = x + y

its type definition is:
 : number -> number -> number

why is it not 

 number number -> number?

What does -> denote exactly.

Thanks in advance.

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