How do you update a map in Pascal Ligo?

Question

I'm trying to learn how to write a smart contract and using Ligo. I'm struggling with quite a few things at the same time e.g. syntax, understand the documentation, best practices etc.

Baby step is, register a user profile i.e. an ipfs hash. So storing this as a map, with the sender being the key and the hash being the value:

type artist is address
type ipfsProfileAddress is string

type artists is map (artist, ipfsProfileAddress)
const artists_storage : artists = map []

// get current address store as artist key and save ipfsProfileAddress
function register_artist (const profile: ipfsProfileAddress) : ipfsProfileAddress is block {
  artists_storage(Tezos.sender, profile)
} with profile

Do I need to instantiate the map first? i.e. create the type, then create an empty one?

How do you set a key -> value?

Thanks

Answer 1

As far as I know, you have to create the default storage for your contract when you deploy it and that's when you will instantiate your storage (and your empty map), so I don't think it is necessary to instantiate it in the contract. Did you try to compile the contract with the instantiated empty map?

I use ReasonLigo more than PascalLigo, but the docs indicate the following way to update a map: artists_storage [(artist: artist)] := ipfsProfileAddress.