-export_type(
[ t/2
+ , exn_class/0
+ , exn_value/1
]).
-export(
, pipe/2
, lift_exn/1
, lift_exn/2
+ , lift_map_exn/3
]).
+-type exn_class() ::
+ error
+ | exit
+ | throw
+ .
+
+-type exn_value(A) ::
+ {exn_class(), A}.
-type t(A, B) ::
{ok, A}
end.
-spec lift_exn(F) -> G
- when F :: fun((A)-> B)
- , G :: fun((A)-> t(B, {Class, Reason :: any()}))
- , Class :: error
- | exit
- | throw
+ when F :: fun((A) -> B)
+ , G :: fun((A) -> t(B, exn_value(any())))
.
lift_exn(F) when is_function(F, 1) ->
- fun(X) ->
- try
- {ok, F(X)}
- catch Class:Reason ->
- {error, {Class, Reason}}
- end
- end.
+ ID = fun hope_fun:id/1,
+ lift_map_exn(F, ID, ID).
+
+-spec lift_exn(F, ErrorTag) -> G
+ when F :: fun((A) -> B)
+ , G :: fun((A) -> t(B, {ErrorTag, exn_value(any())}))
+ .
+lift_exn(F, ErrorTag) when is_function(F, 1) ->
+ ID = fun hope_fun:id/1,
+ Tag = fun (Reason) -> {ErrorTag, Reason} end,
+ lift_map_exn(F, ID, Tag).
--spec lift_exn(F, Label) -> G
- when F :: fun((A)-> B)
- , G :: fun((A)-> t(B, {Label, {Class, Reason :: any()}}))
- , Class :: error
- | exit
- | throw
+-spec lift_map_exn(F, MapOk, MapError) -> G
+ when F :: fun((A) -> B)
+ , MapOk :: fun((B) -> C)
+ , MapError :: fun((exn_value(any())) -> Error)
+ , G :: fun((A) -> t(C, Error))
.
-lift_exn(F, Label) when is_function(F, 1) ->
+lift_map_exn(F, MapOk, MapError) when is_function(F, 1) ->
fun(X) ->
- try
- {ok, F(X)}
- catch Class:Reason ->
- tag_error({error, {Class, Reason}}, Label)
+ Result =
+ try
+ {ok, F(X)}
+ catch Class:Reason ->
+ {error, {Class, Reason}}
+ end,
+ % Applying maps separately as to not unintentionally catch an exception
+ % raised in a map.
+ case Result
+ of {ok , _}=Ok -> map (Ok , MapOk)
+ ; {error, _}=Error -> map_error(Error, MapError)
end
end.