Arizona - a web framework for Erlang/OTP

[carloratm]

I have tried with this sys.config and view, and I get this error:

> rebar3 compile
===> Verifying dependencies...
===> Analyzing applications...
===> Compiling qq
===> Compiling src/home_view.erl failed
src/home_view.erl:none: error in parse transform 'arizona_parse_transform':
exception error: Failed to convert Erlang terms to template in home_view at line 20:
error:function_clause:[{arizona_erl,children_ast_to_html,
                           [{bin,
                                {24,29},
                                [{bin_element,
                                     {24,30},
                                     {string,{24,30},"Arizona Hello World"},
                                     default,
                                     [utf8]}]}],
                           [{file,
                                "/home/carloratm/w/qq/_build/default/lib/arizona/src/arizona_erl.erl"},
                            {line,249}]},
                       {arizona_erl,element_ast_to_html,1,
                           [{file,
                                "/home/carloratm/w/qq/_build/default/lib/arizona/src/arizona_erl.erl"},
                            {line,185}]},
                       {arizona_erl,children_ast_to_html,1,
                           [{file,
                                "/home/carloratm/w/qq/_build/default/lib/arizona/src/arizona_erl.erl"},
                            {line,252}]},
                       {arizona_erl,element_ast_to_html,1,
                           [{file,
                                "/home/carloratm/w/qq/_build/default/lib/arizona/src/arizona_erl.erl"},
                            {line,185}]},
                       {arizona_erl,children_ast_to_html,1,
                           [{file,
                                "/home/carloratm/w/qq/_build/default/lib/arizona/src/arizona_erl.erl"},
                            {line,252}]},
                       {arizona_erl,element_ast_to_html,1,
                           [{file,
                                "/home/carloratm/w/qq/_build/default/lib/arizona/src/arizona_erl.erl"},
                            {line,185}]},
                       {arizona_erl,'-ast_to_html/1-lc$^0/1-0-',1,
                           [{file,
                                "/home/carloratm/w/qq/_build/default/lib/arizona/src/arizona_erl.erl"},
                            {line,94}]},
                       {arizona_erl,'-ast_to_html/1-lc$^0/1-0-',1,
                           [{file,
                                "/home/carloratm/w/qq/_build/default/lib/arizona/src/arizona_erl.erl"},
                            {line,94}]}]
  in function  arizona_parse_transform:transform_from_erl/4 (/home/carloratm/w/qq/_build/default/lib/arizona/src/arizona_parse_transform.erl:549)
     *** Arizona Erlang term template parsing failed
  in call from erl_syntax_lib:'-map/2-lc$^1/1-1-'/2 (erl_syntax_lib.erl:86)
  in call from erl_syntax_lib:'-map/2-lc$^0/1-0-'/2 (erl_syntax_lib.erl:86)
  in call from erl_syntax_lib:'-map/2-lc$^0/1-0-'/2 (erl_syntax_lib.erl:87)
  in call from erl_syntax_lib:map/2 (erl_syntax_lib.erl:87)
  in call from erl_syntax_lib:'-map/2-lc$^1/1-1-'/2 (erl_syntax_lib.erl:86)
  in call from erl_syntax_lib:'-map/2-lc$^0/1-0-'/2 (erl_syntax_lib.erl:86)
  in call from erl_syntax_lib:'-map/2-lc$^0/1-0-'/2 (erl_syntax_lib.erl:87)

I’m on erlang 28.1

[williamthome]

Ensure you have the most up-to-date Arizona code. Run rebar3 unlock arizona && rebar3 upgrade arizona. I made some fixes hours ago. I’m on my phone, so I’m currently unable to check your issue.

[carloratm]

Yeah that was it. Will play with the framework next week.
Expect more feedback.

[williamthome]

@hokan

I’ve personally always preferred the Yaws approach where all the web content is represented as Erlang data, i.e. <Tag> Content </Tag> becomes {Tag, Content}.
This turns the mix of Html and Erlang into plain Erlang, making it easier to work with, as the “Html” can now be easily be composed using regular functions.
This also lets us use regular Erlang indentation & syntax color support in editors.
Additionally we can use regular Erlang tooling to check and test the html generation.

I almost forgot. Thanks for the tip, @hokan! And that’s what I ended up doing:

@williamthome

% Layout is rendered only once when the page loads - it's never updated.
% Only the view content (inserted via render_slot) receives real-time updates.
layout(Bindings) ->
    arizona_template:from_erl([
        ~"<!DOCTYPE html>",
        {html, [], [
            {head, [], [
                {title, [], ~"Arizona Hello World"},
                {script, [{type, ~"module"}], ~"""
                import Arizona from '/assets/arizona/js/arizona.min.js';
                globalThis.arizona = new Arizona();
                arizona.connect('/live');
                """}
            ]},
            {body, [], arizona_template:render_slot(maps:get(main_content, Bindings))}
        ]}
    ]).

render(Bindings) ->
    arizona_template:from_erl(
        {'div', [{id, arizona_template:get_binding(id, Bindings)}], [
            case arizona_template:find_binding(name, Bindings) of
                {ok, Name} ->
                    [~"Hello, ", Name, ~"!"];
                error ->
                    arizona_template:from_erl({button,
                        [{onclick, ~"arizona.pushEvent('hello_world')"}],
                        ~"Say Hello!"
                    })
            end
        ]}
    ).

IMHO, much better! And gives many more possibilities for improvement. Thanks again!

[carloratm]

I went through some of the examples provided, it’s very nice indeed!

Some random thoughts, please take those as random thoughts after 1 day of usage:

1. I tried the rebar plugin to bootstrap a project using the interactive prompt, and if you press a q when asked for the name, it quits. I am not sure that’s a useful tool though, seems very javascript-esque
2. May be possible to have some kind of facade module to shorten the function calls? Something like az:template_erl instead of arizona_template:from_erl?
3. Could be possible to load a template from a file instead of a string?
4. I saw there’s a neovim plugin, does it support vim as well?

Cheers!

[williamthome]

@carloratm

I went through some of the examples provided, it’s very nice indeed!

Thanks!

@carloratm

I tried the rebar plugin to bootstrap a project using the interactive prompt, and if you press a q when asked for the name, it quits.

I need first to sync it with the latest Arizona breaking changes, then I can take a look at the q bug.

@carloratm

I am not sure that’s a useful tool though, seems very javascript-esque

Indeed, the plugin needs improvement. Currently, it’s just a template bootstraping, but I have more ideas for it.

@carloratm

May be possible to have some kind of facade module to shorten the function calls? Something like az:template_erl instead of arizona_template:from_erl?

Yes! That’s something I want to explore. I need to polish the API first to figure out what the best approach would be.

@carloratm

Could be possible to load a template from a file instead of a string?

Yes, but only for HTML and Markdown:

% HTML
arizona_template:from_html({file, "templates/user.html"})
arizona_template:from_html({priv_file, myapp, "templates/user.html"})

% Markdown
arizona_template:from_markdown({file, "content/blog-post.md"})
arizona_template:from_markdown({priv_file, myapp, "content/blog-post.md"})

@carloratm

I saw there’s a neovim plugin, does it support vim as well?

No, unfortunately. The Neovim plugin is specifically for Neovim’s Lua API.

Thanks again for trying out Arizona! I’ll be waiting for more feedback