Debugging: Elm evaluates uncalled `let` variables
If you write a function that has a
let expression variables like so:
view : Model -> Html Msg view model = let logModel = Debug.log "model:" model in div  [ button [ onClick Increment ] [ text "+1" ] , div  [ text <| String.fromInt model.count ] , button [ onClick Decrement ] [ text "-1" ] ]
view function is called you will see the console log message that
logModel writes, even though it was never called from the function's body.
This can be useful for debugging function arguments coming in, or other variables without messing with the function's body.
To avoid the
[elm-analyse 97] [W] Unused variable "logModel" warning you can use an underscore instead of naming the variable:
example = let _ = Debug.log "foo" "bar" in "function body"
It is worth mentioning that variables that are called from a function's body will only be executed once.
example = let foo = Debug.log "foo" "I'm called once" bar = Debug.log "bar" "I'm called once" in bar
will result in only two console log messages, one for
foo, and one for
h/t Jeremy FairbankTweet