CODEWITHSUNDEEP
haskellfunctional-programmingelm
Eben Kadile
Eben Kadile

Reputation: 779

Haskell pattern matching not allowed in Elm?

Following this Elm tutorial and 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 would define it the same way but with syntax I prefer:

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

But this doesn't compile, does Elm not support this syntax or did I make a mistake?

Upvotes: 5

Views: 251

Answers (1)

Jan Tojnar
Jan Tojnar

Reputation: 5524

One of the goals of Elm is to use a consistent style; removing redundant syntax is a conclusion of this. For that reason, you will not find any where clause and function definitions with multiple variants are not permitted either.

Upvotes: 12

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