Merge pull request #226 from roc-lang/error-type-fixes

error unification fixes

Author: Anton-4

examples/args.roc

@@ -12,7 +12,7 @@ import pf.Arg.Param as Param
 import pf.Arg
 
 main =
-    args = Arg.list!
+    args = Arg.list! {}
 
     when Cli.parseOrDisplayMessage cli args is
         Ok { command: subcommand } ->

flake.lock

@@ -10,8 +10,9 @@ import Arg.ErrorFormatter exposing [formatArgExtractErr]
 import Arg.Help exposing [helpText, usageHelp]
 
 ## Gives a list of the program's command-line arguments.
-list : Task (List Str) []_
-list =
+## `{} ->` is a necessary workaround to make error accumulation/unification work.
+list : {} -> Task (List Str) []
+list = \_ ->
     Effect.args
     |> Effect.map Ok
     |> InternalTask.fromEffect
@@ -82,7 +83,7 @@ list =
 ## ```
 parse : CliParser state -> Task state [Exit I32 Str, StdoutErr Stdout.Err]
 parse = \parser ->
-    when parser.parser list! is
+    when parser.parser (list {})! is
         SuccessfullyParsed data ->
             Task.ok data
 

platform/Arg.roc

@@ -85,7 +85,7 @@ cwd : Effect (List U8)
 sendRequest : Box InternalHttp.Request -> Effect InternalHttp.InternalResponse
 
 tcpConnect : Str, U16 -> Effect (Result U64 Str)
-tcpClose : U64 -> Effect (Result {} *)
+tcpClose : U64 -> Effect {}
 tcpReadUpTo : U64, U64 -> Effect (Result (List U8) Str)
 tcpReadExactly : U64, U64 -> Effect (Result (List U8) Str)
 tcpReadUntil : U64, U8 -> Effect (Result (List U8) Str)

platform/Effect.roc

@@ -112,9 +112,10 @@ connect = \host, port ->
         |> Result.mapErr parseConnectErr
     |> InternalTask.fromEffect
 
-close : Stream -> Task {} *
+close : Stream -> Task {} []
 close = \@Stream stream ->
     Effect.tcpClose stream
+    |> Effect.map Ok
     |> InternalTask.fromEffect
 
 ## Read up to a number of bytes from the TCP stream.

platform/Tcp.roc

@@ -989,12 +989,10 @@ pub extern "C" fn roc_fx_tcpConnect(
 }
 
 #[no_mangle]
-pub extern "C" fn roc_fx_tcpClose(stream_id: u64) -> RocResult<(), ()> {
+pub extern "C" fn roc_fx_tcpClose(stream_id: u64) {
     TCP_STREAMS.with(|tcp_streams_local| {
         tcp_streams_local.borrow_mut().remove(&stream_id);
-    });
-
-    RocResult::ok(())
+    })
 }
 
 #[no_mangle]