Haskell pattern matching not allowed in Elm?

Question

Following this Elm tutorial , I assumed that the function

update : Msg -> Model -> Model

is defined in the tutorial as

update msg model = 
    case msg of
        Increment  -> model + 1
        Deccrement -> model - 1
        Reset      -> 0

I thought I'd define it the same way, but with the syntax that I prefer:

update Increment model = model + 1
update Decrement model = model - 1
update Reset model     = 0

But it doesn't compile, doesn't this syntax help Elm or am I wrong?

+3

Eben cowley June 21. 17 at 4:44

1 answer

Jan Tojnar · Accepted Answer · 2017-06-21T05:13:40+0000

One of Elm's goals is to use a consistent style ; outputting redundant syntax is the end of this. For this reason, you won't find any where

clause and multi-choice function definitions are also not allowed.