cat ~/.zshrc
#. /usr/local/lib/erlang/27.1/activate
# remove the line above from zshrc

whereis erl 
#erl: /usr/local/lib/erlang/27.1/bin/erl
whereis lfe
#lfe: /usr/local/bin/lfe /usr/local/lib/lfe

rm -rf /usr/local/lib/erlang
rm -rf /usr/local/bin/lfe
rm -rf /usr/local/lib/lfe

cd /usr/local/lib
sudo mkdir erlang
sudo chmod 777 erlang
cd erlang
kerl build 27.1
kerl install 27.1 /usr/local/lib/erlang
# Installing Erlang/OTP 27.1 (27.1) in /usr/local/lib/erlang...
# Initializing (install) log file at /home/debian/.kerl/builds/27.1/otp_install_27.1.log.
# You can activate this installation running the following command:
# . /usr/local/lib/erlang/activate
# Later on, you can leave the installation typing:
# kerl_deactivate

nano ~/.zshrc
#. /usr/local/lib/erlang/activate



kerl list releases

APPLICATIONS DISABLED (See: /home/debian/.kerl/builds/27.1/otp_build_27.1.log)
 * jinterface     : No Java compiler found
 * odbc           : ODBC library - link check failed

APPLICATIONS INFORMATION (See: /home/debian/.kerl/builds/27.1/otp_build_27.1.log)
 * wx             : wxWidgets was not compiled with --enable-webview or wxWebView developer package is not installed, wxWebView will NOT be available

lsb_release -a
# search libwxgtk-webview
sudo apt install libwxgtk-webview3.0-gtk3-dev
``

in a headless remote server

```bash
sudo apt-get install xvfb
Xvfb :1 -screen 0 1024x768x24 &
export DISPLAY=:1

in erlang
os:putenv("DISPLAY", ":1").
wx:new().

git clone https://github.com/lfe/lfe.git
cd lfe
make compile
make install PREFIX=$HOME/.local

rebar3 new lfe-app thecowboyex

(defun start (_Type _Args)
  (application:ensure_all_started 'cowboy)
  (let* ([Dispatch (cowboy_router:compile (list (tuple '_ (list (tuple "/" 'hello_handler '())))))]
          [(tuple 'ok _) (cowboy:start_clear 'my_http_listener 
                            (list (tuple 'port 8081)) 
                            (map 'env (map 'dispatch Dispatch)) )]
                            )
    (thecowboyex-sup:start_link)                        
    )
)

(defmodule hello_handler
  ;; Cowboy handler
  (export (init 2)
  (terminate 2)
  ))

;;;===================================================================
;;; Cowboy handler
;;;===================================================================
(defun init (req0 state) 
  (let ((req (cowboy_req:reply 200 #M(#"content-type" #"text/javascript") 
  (binary """ 
  <h1>Hello</h1>
  <p>Go yourself</p>
  """)
  req0)))
    (tuple 'ok req state)
    ))
(defun terminate (_req _state) 'ok)

rebar3 lfe repl
(thecowboyex-app:start 'normal '())

{erl_opts, [debug_info]}.
{provider_hooks, [{pre, [{compile, {lfe, compile}}]}]}.

{deps, [
    {lfe, "~> 2.1"},
    {ltest, "~> 0.13"},
    {cowboy, "~> 2.12.0"}
]}.
{plugins, [
    {rebar3_lfe, "~> 0.4.11"}
]}.
{shell, [
    %% {config, "config/sys.config"},
    {apps, [thecowboyex]}
]}.

{application, thecowboyex, [
    {description, "An OTP application"},
    {vsn, "0.1.0"},
    {registered, [thecowboyex]},
    {mod, {thecowboyex_app, []}},
    {applications, [
        kernel,
        stdlib,
        cowboy
    ]},
    {env, []},
    {modules, []},
    {licenses, ["Apache-2.0"]},
    {links, []}
 ]}.

(defmodule thecowboyex_app
  (behaviour application)
  ;; app implementation
  (export
   (start 2)
   (stop 1)))

;;; --------------------------
;;; application implementation
;;; --------------------------

(defun start (_Type _Args)
  (application:ensure_all_started 'cowboy)
  (let* ([Dispatch (cowboy_router:compile (list (tuple '_ (list (tuple "/" 'hello_handler '())))))]
          [(tuple 'ok _) (cowboy:start_clear 'my_http_listener 
                            (list (tuple 'port 8080)) 
                            (map 'env (map 'dispatch Dispatch)) )]
                            )
    (thecowboyex_sup:start_link)                        
    )
)

(defun stop (_state)
  (my-lfe-app-sup:stop)
  'ok)

(defmodule hello_handler
  ;; Cowboy handler
  (export (init 2)
  (terminate 2)
  ))

;;;===================================================================
;;; Cowboy handler
;;;===================================================================
(defun init (req0 state) 
  (let ((req (cowboy_req:reply 200 #M(#"content-type" #"text/javascript") 
  (binary """ 
  <h1>Hello</h1>
  <p>Go yourself</p>
  """)
  req0)))
    (tuple 'ok req state)
    ))
(defun terminate (_req _state) 'ok)

{erl_opts, [debug_info]}.
{deps, []}.

{plugins, [
{rebar3_lfe, "0.4.10"}
]}.
{shell, [
    %% {config, "config/sys.config"},
     
    % {apps, [my_lfe_app]}
]}.

rebar3 plugins update

rebar3 new lfe-app my_lfe_app
# or
rebar3 new lfe-lib my_lfe_library

cd my_lfe_app
rebar3 compile
rebar3 lfe repl

rebar3 new release mycowboyapp
cd mycowboyapp
nano rebar.config
rebar3 compile

{deps, [
    {cowboy, {git, "https://github.com/ninenines/cowboy", {tag, "2.12.0"}}}
    ]}.

{plugins, [
    {rebar3_lfe, "0.4.9"}
]}.

{erl_opts, [debug_info]}.
{deps, [
    {cowboy, {git, "https://github.com/ninenines/cowboy", {tag, "2.12.0"}}}
    ]}.

{plugins, [
    {rebar3_lfe, "0.4.9"}
]}.

{relx, [
    {release, {cowboyex, "0.1.0"}, [
        cowboyex,
        sasl
    ]},

    {mode, dev},

    %% automatically picked up if the files
    %% exist but can be set manually, which
    %% is required if the names aren't exactly
    %% sys.config and vm.args
    {sys_config, "./config/sys.config"},
    {vm_args, "./config/vm.args"}

    %% the .src form of the configuration files do
    %% not require setting RELX_REPLACE_OS_VARS
    %% {sys_config_src, "./config/sys.config.src"},
    %% {vm_args_src, "./config/vm.args.src"}
]}.

{profiles, [
    %% prod is the default mode when prod
    %% profile is used, so does not have
    %% to be explicitly included like this
    {prod, [
        {relx, [
            {mode, prod}

            %% use minimal mode to exclude ERTS
            %% {mode, minimal}
        ]}
    ]}
]}.

;; Start the TCP server
(defmodule sample
  (export all)
  )
(defun start (Port)
(let (((tuple ok ListenSocket) (gen_tcp:listen Port '(binary #(packet 0) #(active false) #(reuseaddr true))) ))
(io:format "listening on port ~p ~n" `(,Port))
(loop ListenSocket)
    ) 
)
(defun loop (ListenSocket)
    (let ((
            (tuple ok Socket ) (gen_tcp:accept ListenSocket)
            ))
    (spawn (lambda () (handle-connection Socket)))
    (loop ListenSocket)
    )
)
(defun handle-connection (Socket)
    (case (gen_tcp:recv Socket 0)
        ((tuple ok Data) 
            (io:format `(,Data))
            (gen_tcp:send Socket "Hi this is Http 0.9")
            (gen_tcp:close Socket)
        )
        ((tuple error Reason) 
            (io:format `(,Reason))
            (gen_tcp:close Socket)
            )
        )
)

 spawn(fun() -> self() ! {done} end). 

 (spawn (lambda () (! (self) (tuple "done"))))

spawn(sample7, loop, [{done}])