I'm a bit confused how to modify an item in a list. This is my structure:
type alias Player =
{ id : Int
, name : String
, isActive : Bool
}
type alias Model =
{ players : List Player
, newPlayer : Player
}
So I have a list of Players, and I want to edit a specific Player in the list (for example changing Player with Id = 2 field "isActive" to True). How could I go about this?
CodePudding user response:
As a helper, you can consider using List.Extra.updateIf
newPlayers = players
|> List.Extra.updateIf (\player -> player.id == 2) (\player -> { player | isActive = True })
CodePudding user response:
One solution is to use List.map
:
setIsActiveForPlayer : List Player -> Int -> Bool -> List Player
setIsActiveForPlayer players id isActive =
let
update player =
if player.id == id then
{ player | isActive = isActive }
else
player
in
players |> List.map update
Another solution performs the iteration “by hand”:
setIsActiveForPlayer : List Player -> Int -> Bool -> List Player
setIsActiveForPlayer players id isActive =
case players of
[] ->
[]
player :: rest ->
if player.id == id then
{ player | isActive = isActive } :: rest
else
player :: setActivePlayer rest id isActive
This should be slightly more efficient because it reuses the tail of the list following the updated player.