I think I have something close to what you're looking for, but my solution
makes me wonder, *why store text in your model rather than the parsed
float/int values?* It seems like you want the parsed values for a
calculation, not to format a paragraph of text.
update : Msg -> Model -> Model
update msg model =
case msg of
ChangeDripText dripText ->
{ model
| dripText = valueOrDefault model.dripText String.toFloat dripText
}
ChangeHoursText simulationHoursText ->
{ model
| simulationHoursText = valueOrDefault model.simulationHoursText
String.toInt simulationHoursText
}
ChangeMinutesText simulationMinutesText ->
{ model
| simulationMinutesText = valueOrDefault
model.simulationMinutesText String.toInt simulationMinutesText
}
valueOrDefault : a -> (a -> Result x b) -> a -> a
valueOrDefault default test value =
test value
|> Result.map (always value)
|> Result.withDefault default
On Wednesday, October 19, 2016 at 10:49:03 AM UTC-4, Brian Marick wrote:
>
> I have a model that looks like this:
>
> type alias Model =
> { ...
> , dripText : String
> , simulationHoursText : String
> , simulationMinutesText : String
> ...
> }
>
> Those strings each correspond to a text field containing floating point
> numbers. The whole thing looks like this:
>
>
> The text fields ensure that the values are all valid when characters are
> typed, using `onInput` messages. I would very much like to write something
> like:
>
> — Ignore the fact that this `update` doesn’t return
> — a `Cmd Msg`. That’s coming.
> update : Msg -> Model -> Model
> update msg model =
> case msg of
> ChangedDripText string ->
> updateWhen isValidFloatString dripText string
> ChangedHoursText string ->
> updateWhen isValidIntString simulationHoursText string
> ChangedMinutesText string ->
> updateWhen isValidIntString simulationMinutesText string
>
> … because that shows what’s different about each case. (Especially useful
> is highlighting which fields accept integers and which floats.)
>
> However, I think - based on
> https://lexi-lambda.github.io/blog/2015/11/06/functionally-updating-record-types-in-elm/
>
> - there’s no way to do that. Which has me writing this copypasta:
>
> updateNextSpeed model nextString =
> if isValidFloatString nextString then
> {model | dripText = nextString }
> else
> model
>
> updateHours model nextString =
> if isValidIntString nextString then
> {model | simulationHoursText = nextString }
> else
> model
>
> updateMinutes model nextString =
> if isValidIntString nextString then
> {model | simulationMinutesText = nextString }
> else
> model
>
>
> update : Msg -> Model -> Model
> update msg model =
> case msg of
> ChangedDripText string ->
> updateNextSpeed model string
> ChangedHoursText string ->
> updateHours model string
> ChangedMinutesText string ->
> updateMinutes model string
>
> Is there a better way to handle this?
>
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