How do I elegantly check many conditions in Erlang?

Question

So when a user sends a request to register an account, they send their username, password, email, and other info. The registration function must verify all of their data. An

Answer 1

Building up on @JLarky's answer, here's something that i came up with. It also draws some inspiration from Haskell's monads.

-record(user,
    {name :: binary(), 
     email :: binary(), 
     password :: binary()}
).
-type user() :: #user{}.
-type bind_res() :: {ok, term()} | {error, term()} | term().
-type bind_fun() :: fun((term()) -> bind_res()).


-spec validate(term(), [bind_fun()]) -> bind_res().
validate(Init, Functions) ->
    lists:foldl(fun '|>'/2, Init, Functions).

-spec '|>'(bind_fun(), bind_res())-> bind_res().
'|>'(F, {ok, Result}) -> F(Result);
'|>'(F, {error, What} = Error) -> Error;
'|>'(F, Result) -> F(Result).

-spec validate_email(user()) -> {ok, user()} | {error, term()}. 
validate_email(#user{email = Email}) ->
...
-spec validate_username(user()) -> {ok, user()} | {error, term()}.
validate_username(#user{name = Name}) ->
...
-spec validate_password(user()) -> {ok, user()} | {error, term()}.    
validate_password(#user{password = Password}) ->
...

validate(#user{...}, [
    fun validate_email/1,
    fun validate_username/1,
    fun validate_password/1
]).