src/hope_result.erl

   1 -module(hope_result).
   2
   3
   4 -export_type(
   5     [ t/2
   6     ]).
   7
   8 -export(
   9     [ pipe/2
  10     , lift_exn/1
  11     ]).
  12
  13
  14 -type t(A, B) ::
  15       {ok, A}
  16     | {error, B}
  17     .
  18
  19
  20 -spec pipe([F], X) ->
  21     t(Ok, Error)
  22     when X     :: any()
  23        , Ok    :: any()
  24        , Error :: any()
  25        , F     :: fun((X) -> t(Ok, Error))
  26        .
  27 pipe([]    , X) -> X;
  28 pipe([F|Fs], X) ->
  29     case F(X)
  30     of  {error, _}=E -> E
  31     ;   {ok, Y}      -> pipe(Fs, Y)
  32     end.
  33
  34 -spec lift_exn(F) -> G
  35     when F     :: fun((A)-> B)
  36        , G     :: fun((A)-> t(B, {Class, Reason :: any()}))
  37        , Class :: error
  38                 | exit
  39                 | throw
  40        .
  41 lift_exn(F) when is_function(F, 1) ->
  42     fun(X) ->
  43         try
  44             {ok, F(X)}
  45         catch Class:Reason ->
  46             {error, {Class, Reason}}
  47         end
  48     end.