Reverse the order of Error and FatalError parameters in the Result

In other usage, I discovered that it's rather confusing to have the parameters in the order that they were in. It feels better to have the fatal error after the regular error.

Cargo.lock

@@ -861,13 +861,6 @@ dependencies = [
  "miniz_oxide 0.7.1",
 ]
 
-[[package]]
-name = "flow"
-version = "0.1.0"
-dependencies = [
- "thiserror",
-]
-
 [[package]]
 name = "fluent"
 version = "0.16.0"
@@ -3119,6 +3112,13 @@ dependencies = [
  "winreg",
 ]
 
+[[package]]
+name = "result-extended"
+version = "0.1.0"
+dependencies = [
+ "thiserror",
+]
+
 [[package]]
 name = "rsa"
 version = "0.9.2"

Cargo.toml

@@ -8,7 +8,6 @@ members = [
     "dashboard",
     "emseries",
     "file-service",
-    "flow",
     "fluent-ergonomics",
     "geo-types",
     "gm-control-panel",
@@ -17,7 +16,8 @@ members = [
     "kifu/core",
     "kifu/gtk",
     "memorycache",
+    "nom-training",
+    "result-extended",
     "screenplay",
     "sgf",
-    "nom-training",
 ]

build.sh

@@ -11,7 +11,6 @@ RUST_ALL_TARGETS=(
     "dashboard"
     "emseries"
     "file-service"
-    "flow"
     "fluent-ergonomics"
     "geo-types"
     "gm-control-panel"
@@ -20,6 +19,8 @@ RUST_ALL_TARGETS=(
     "kifu-core"
     "kifu-gtk"
     "memorycache"
+    "nom-training"
+    "result-extended"
     "screenplay"
     "sgf"
 )

result-extended/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "flow"
+name = "result-extended"
 version = "0.1.0"
 edition = "2021"
 license = "GPL-3.0-only"

result-extended/src/lib.rs

@@ -33,84 +33,84 @@ use std::{error::Error, fmt};
 /// statement.
 pub trait FatalError: Error {}
 
-/// Flow<A, FE, E> represents a return value that might be a success, might be a fatal error, or
+/// Result<A, FE, E> represents a return value that might be a success, might be a fatal error, or
 /// might be a normal handleable error.
-pub enum Flow<A, FE, E> {
+pub enum Result<A, E, FE> {
     /// The operation was successful
     Ok(A),
+    /// Ordinary errors. These should be handled and the application should recover gracefully.
+    Err(E),
     /// The operation encountered a fatal error. These should be bubbled up to a level that can
     /// safely shut the application down.
     Fatal(FE),
-    /// Ordinary errors. These should be handled and the application should recover gracefully.
-    Err(E),
 }
 
-impl<A, FE, E> Flow<A, FE, E> {
+impl<A, E, FE> Result<A, E, FE> {
     /// Apply an infallible function to a successful value.
-    pub fn map<B, O>(self, mapper: O) -> Flow<B, FE, E>
+    pub fn map<B, O>(self, mapper: O) -> Result<B, E, FE>
     where
         O: FnOnce(A) -> B,
     {
         match self {
-            Flow::Ok(val) => Flow::Ok(mapper(val)),
-            Flow::Fatal(err) => Flow::Fatal(err),
-            Flow::Err(err) => Flow::Err(err),
+            Result::Ok(val) => Result::Ok(mapper(val)),
+            Result::Err(err) => Result::Err(err),
+            Result::Fatal(err) => Result::Fatal(err),
         }
     }
 
     /// Apply a potentially fallible function to a successful value.
     ///
     /// Like `Result.and_then`, the mapping function can itself fail.
-    pub fn and_then<B, O>(self, handler: O) -> Flow<B, FE, E>
+    pub fn and_then<B, O>(self, handler: O) -> Result<B, E, FE>
     where
-        O: FnOnce(A) -> Flow<B, FE, E>,
+        O: FnOnce(A) -> Result<B, E, FE>,
     {
         match self {
-            Flow::Ok(val) => handler(val),
-            Flow::Fatal(err) => Flow::Fatal(err),
-            Flow::Err(err) => Flow::Err(err),
+            Result::Ok(val) => handler(val),
+            Result::Err(err) => Result::Err(err),
+            Result::Fatal(err) => Result::Fatal(err),
         }
     }
 
     /// Map a normal error from one type to another. This is useful for converting an error from
     /// one type to another, especially in re-throwing an underlying error. `?` syntax does not
-    /// work with `Flow`, so you will likely need to use this a lot.
-    pub fn map_err<F, O>(self, mapper: O) -> Flow<A, FE, F>
+    /// work with `Result`, so you will likely need to use this a lot.
+    pub fn map_err<F, O>(self, mapper: O) -> Result<A, F, FE>
     where
         O: FnOnce(E) -> F,
     {
         match self {
-            Flow::Ok(val) => Flow::Ok(val),
-            Flow::Fatal(err) => Flow::Fatal(err),
-            Flow::Err(err) => Flow::Err(mapper(err)),
+            Result::Ok(val) => Result::Ok(val),
+            Result::Err(err) => Result::Err(mapper(err)),
+            Result::Fatal(err) => Result::Fatal(err),
         }
     }
 
     /// Provide a function to use to recover from (or simply re-throw) an error.
-    pub fn or_else<O, F>(self, handler: O) -> Flow<A, FE, F>
+    pub fn or_else<O, F>(self, handler: O) -> Result<A, F, FE>
     where
-        O: FnOnce(E) -> Flow<A, FE, F>,
+        O: FnOnce(E) -> Result<A, F, FE>,
     {
         match self {
-            Flow::Ok(val) => Flow::Ok(val),
-            Flow::Fatal(err) => Flow::Fatal(err),
-            Flow::Err(err) => handler(err),
+            Result::Ok(val) => Result::Ok(val),
+            Result::Err(err) => handler(err),
+            Result::Fatal(err) => Result::Fatal(err),
         }
     }
 }
 
-/// Convert from a normal `Result` type to a `Flow` type. The error condition for a `Result` will
-/// be treated as `Flow::Err`, never `Flow::Fatal`.
-impl<A, FE, E> From<Result<A, E>> for Flow<A, FE, E> {
-    fn from(r: Result<A, E>) -> Self {
+/// Convert from a normal `Result` type to a `Result` type. The error condition for a `Result` will
+/// be treated as `Result::Err`, never `Result::Fatal`.
+impl<A, E, FE> From<std::result::Result<A, E>> for Result<A, E, FE> {
+    fn from(r: std::result::Result<A, E>) -> Self {
         match r {
-            Ok(val) => Flow::Ok(val),
-            Err(err) => Flow::Err(err),
+            Ok(val) => Result::Ok(val),
+            Err(err) => Result::Err(err),
         }
     }
 }
 
-impl<A, FE, E> fmt::Debug for Flow<A, FE, E>
+impl<A, E, FE> fmt::Debug for Result<A, E, FE>
 where
     A: fmt::Debug,
     FE: fmt::Debug,
@@ -118,14 +118,14 @@ where
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            Flow::Ok(val) => f.write_fmt(format_args!("Flow::Ok {:?}", val)),
-            Flow::Err(err) => f.write_fmt(format_args!("Flow::Err {:?}", err)),
-            Flow::Fatal(err) => f.write_fmt(format_args!("Flow::Fatal {:?}", err)),
+            Result::Ok(val) => f.write_fmt(format_args!("Result::Ok {:?}", val)),
+            Result::Err(err) => f.write_fmt(format_args!("Result::Err {:?}", err)),
+            Result::Fatal(err) => f.write_fmt(format_args!("Result::Fatal {:?}", err)),
         }
     }
 }
 
-impl<A, FE, E> PartialEq for Flow<A, FE, E>
+impl<A, E, FE> PartialEq for Result<A, E, FE>
 where
     A: PartialEq,
     FE: PartialEq,
@@ -133,27 +133,27 @@ where
 {
     fn eq(&self, rhs: &Self) -> bool {
         match (self, rhs) {
-            (Flow::Ok(val), Flow::Ok(rhs)) => val == rhs,
-            (Flow::Err(_), Flow::Err(_)) => true,
-            (Flow::Fatal(_), Flow::Fatal(_)) => true,
+            (Result::Ok(val), Result::Ok(rhs)) => val == rhs,
+            (Result::Err(_), Result::Err(_)) => true,
+            (Result::Fatal(_), Result::Fatal(_)) => true,
             _ => false,
         }
     }
 }
 
 /// Convenience function to create an ok value.
-pub fn ok<A, FE: FatalError, E: Error>(val: A) -> Flow<A, FE, E> {
-    Flow::Ok(val)
+pub fn ok<A, E: Error, FE: FatalError>(val: A) -> Result<A, E, FE> {
+    Result::Ok(val)
 }
 
 /// Convenience function to create an error value.
-pub fn error<A, FE: FatalError, E: Error>(err: E) -> Flow<A, FE, E> {
-    Flow::Err(err)
+pub fn error<A, E: Error, FE: FatalError>(err: E) -> Result<A, E, FE> {
+    Result::Err(err)
 }
 
 /// Convenience function to create a fatal value.
-pub fn fatal<A, FE: FatalError, E: Error>(err: FE) -> Flow<A, FE, E> {
-    Flow::Fatal(err)
+pub fn fatal<A, E: Error, FE: FatalError>(err: FE) -> Result<A, E, FE> {
+    Result::Fatal(err)
 }
 
 /// Return early from the current function if the value is a fatal error.
@@ -161,9 +161,9 @@ pub fn fatal<A, FE: FatalError, E: Error>(err: FE) -> Flow<A, FE, E> {
 macro_rules! return_fatal {
     ($x:expr) => {
         match $x {
-            Flow::Fatal(err) => return Flow::Fatal(err),
-            Flow::Err(err) => Err(err),
-            Flow::Ok(val) => Ok(val),
+            Result::Fatal(err) => return Result::Fatal(err),
+            Result::Err(err) => Err(err),
+            Result::Ok(val) => Ok(val),
         }
     };
 }
@@ -173,9 +173,9 @@ macro_rules! return_fatal {
 macro_rules! return_error {
     ($x:expr) => {
         match $x {
-            Flow::Ok(val) => val,
-            Flow::Err(err) => return Flow::Err(err),
-            Flow::Fatal(err) => return Flow::Fatal(err),
+            Result::Ok(val) => val,
+            Result::Err(err) => return Result::Err(err),
+            Result::Fatal(err) => return Result::Fatal(err),
         }
     };
 }
@@ -210,45 +210,45 @@ mod test {
 
     #[test]
     fn it_can_map_things() {
-        let success: Flow<i32, FatalError, Error> = ok(15);
+        let success: Result<i32, Error, FatalError> = ok(15);
         assert_eq!(ok(16), success.map(|v| v + 1));
     }
 
     #[test]
     fn it_can_chain_success() {
-        let success: Flow<i32, FatalError, Error> = ok(15);
+        let success: Result<i32, Error, FatalError> = ok(15);
         assert_eq!(ok(16), success.and_then(|v| ok(v + 1)));
     }
 
     #[test]
     fn it_can_handle_an_error() {
-        let failure: Flow<i32, FatalError, Error> = error(Error::Error);
+        let failure: Result<i32, Error, FatalError> = error(Error::Error);
         assert_eq!(
-            ok::<i32, FatalError, Error>(16),
+            ok::<i32, Error, FatalError>(16),
             failure.or_else(|_| ok(16))
         );
     }
 
     #[test]
     fn early_exit_on_fatal() {
-        fn ok_func() -> Flow<i32, FatalError, Error> {
-            let value = return_fatal!(ok::<i32, FatalError, Error>(15));
+        fn ok_func() -> Result<i32, Error, FatalError> {
+            let value = return_fatal!(ok::<i32, Error, FatalError>(15));
             match value {
                 Ok(_) => ok(14),
                 Err(err) => error(err),
             }
         }
 
-        fn err_func() -> Flow<i32, FatalError, Error> {
-            let value = return_fatal!(error::<i32, FatalError, Error>(Error::Error));
+        fn err_func() -> Result<i32, Error, FatalError> {
+            let value = return_fatal!(error::<i32, Error, FatalError>(Error::Error));
             match value {
                 Ok(_) => panic!("shouldn't have gotten here"),
                 Err(_) => ok(0),
             }
         }
 
-        fn fatal_func() -> Flow<i32, FatalError, Error> {
-            return_fatal!(fatal::<i32, FatalError, Error>(FatalError::FatalError));
+        fn fatal_func() -> Result<i32, Error, FatalError> {
+            let _ = return_fatal!(fatal::<i32, Error, FatalError>(FatalError::FatalError));
             panic!("failed to bail");
         }
 
@@ -259,19 +259,19 @@ mod test {
 
     #[test]
     fn it_can_early_exit_on_all_errors() {
-        fn ok_func() -> Flow<i32, FatalError, Error> {
-            let value = return_error!(ok::<i32, FatalError, Error>(15));
+        fn ok_func() -> Result<i32, Error, FatalError> {
+            let value = return_error!(ok::<i32, Error, FatalError>(15));
             assert_eq!(value, 15);
             ok(14)
         }
 
-        fn err_func() -> Flow<i32, FatalError, Error> {
-            return_error!(error::<i32, FatalError, Error>(Error::Error));
+        fn err_func() -> Result<i32, Error, FatalError> {
+            return_error!(error::<i32, Error, FatalError>(Error::Error));
             panic!("failed to bail");
         }
 
-        fn fatal_func() -> Flow<i32, FatalError, Error> {
-            return_error!(fatal::<i32, FatalError, Error>(FatalError::FatalError));
+        fn fatal_func() -> Result<i32, Error, FatalError> {
+            return_error!(fatal::<i32, Error, FatalError>(FatalError::FatalError));
             panic!("failed to bail");
         }