The config approach pops up various places — e.g., elm-sortable-table — but isn't as well specified anywhere that I've seen because it doesn't have as clear a pattern to specify.
Cmd.map (and Html,map) come out of what could be called Classic TEA. The classic Elm architecture was built to allow decomposition by using tagged messages to route through the compound model. For example, if you wanted to have a number of pages, you could have a top level model that served as a page switcher and it would use tagged messages to route to the current page (or to discard messages if they weren't bound for the current page). This worked well though I know programmers who grouse at the amount of message routing boilerplate one has to write. But then people started trying to build React style component models with this and had trouble. At which point, various people in the Elm community decided that nesting was a bad idea and advocated strongly for flatness with functions being the only decomposition mechanism and those without much in the way of architectural guidance. Basically, this was a case of the pendulum swinging wildly and the architecture for building complex applications seemingly getting cast aside without a replacement. My advice would be to use the message routing patterns from classic TEA in the places it makes sense to break ones app apart — just know that it isn't particularly well suited to building components. For example, our codebase contains a module providing a model and corresponding messages and update function for managing the sign up/sign in process. It knows how to talk to our server. It knows what validation to do. It understands the errors coming back from the server. It knows nothing about how to display the data and instead provides a function to fill in a ViewData structure that contains the information needed by the view code. We can now reuse this logic in a variety of places where we need SUSI logic. Each of those hosting cases then routes messages to and from the logic using a message case of the form `ToLogic Logic.Msg` and using `Cmd.map ToLogic` to promote logic layer messages to view layer messages. Mark On Wed, Mar 29, 2017 at 11:50 AM, Juan Ibiapina <[email protected]> wrote: > Where can I find more information about that Config approach? I'm not able > to find a way to organise multiple page applications that I like. > > On Wed, Mar 29, 2017 at 6:24 AM, Peter Damoc <[email protected]> wrote: > >> If you have a series of pages that each has Cmds and you have these pages >> unified under one app, you need to lift each page Cmd to become an app Cmd. >> >> There used to be a nesting architecture where this was demonstrated but >> now that's been dropped in favor of the Config approach. >> >> >> >> On Wed, Mar 29, 2017 at 1:09 AM, Brian Marick <[email protected]> >> wrote: >> >>> I’m having trouble thinking of a scenario in which you’d use `Cmd.map`. >>> >>> Is it for a case where you create a `Cmd a` where `a` is something >>> different than the usual `Msg`, then transform it into a `Msg`? (When would >>> you do such a thing?) >>> >>> Or for a case where you want to change the `Msg` constructor that `Cmd` >>> “wraps”? (Ditto.) >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Elm Discuss" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> >> >> -- >> There is NO FATE, we are the creators. >> blog: http://damoc.ro/ >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Elm Discuss" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > Juan > > -- > You received this message because you are subscribed to the Google Groups > "Elm Discuss" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Elm Discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
