Proper try keyword

crates/cli/src/main.rs

@@ -247,6 +247,8 @@ fn main() -> io::Result<()> {
                         ) {
                             Ok((problems, total_time)) => {
                                 problems.print_error_warning_count(total_time);
+                                println!(".\n");
+
                                 exit_code = problems.exit_code();
                             }
 

crates/cli/tests/cli_tests.rs

@@ -334,7 +334,7 @@ mod cli_tests {
             );
 
             let expected_out =
-                "0 error and 0 warning found in <ignored for test> ms\n0 error and 0 warning found in <ignored for test> ms\n";
+                "0 errors and 0 warnings found in <ignored for test> ms.\n\n0 errors and 0 warnings found in <ignored for test> ms.\n\n";
 
             cli_build.run().assert_clean_stdout(expected_out);
         }

crates/cli/tests/snapshots/cli_tests__cli_tests__test_platform_simple_zig__module_params_arity_mismatch.snap

@@ -1,7 +1,7 @@
 ---
 source: crates/cli/tests/cli_tests.rs
-assertion_line: 429
 expression: cli_dev_out.normalize_stdout_and_stderr()
+snapshot_kind: text
 ---
 
 ── TOO MANY ARGS in tests/test-projects/module_params/arity_mismatch.roc ───────
@@ -36,8 +36,6 @@ make partial application explicit.
 
 ────────────────────────────────────────────────────────────────────────────────
 
-3 error and 0 warning found in <ignored for test> ms
-.
+3 errors and 0 warnings found in <ignored for test> ms.
 
 You can run <ignored for tests>
-

crates/cli/tests/snapshots/cli_tests__cli_tests__test_platform_simple_zig__module_params_bad_ann.snap

@@ -1,7 +1,7 @@
 ---
 source: crates/cli/tests/cli_tests.rs
-assertion_line: 445
 expression: cli_dev_out.normalize_stdout_and_stderr()
+snapshot_kind: text
 ---
 
 ── TYPE MISMATCH in tests/test-projects/module_params/BadAnn.roc ───────────────
@@ -41,8 +41,6 @@ Tip: It looks like it takes too many arguments. I'm seeing 1 extra.
 
 ────────────────────────────────────────────────────────────────────────────────
 
-2 error and 1 warning found in <ignored for test> ms
-.
+2 errors and 1 warning found in <ignored for test> ms.
 
 You can run <ignored for tests>
-

crates/cli/tests/snapshots/cli_tests__cli_tests__test_platform_simple_zig__module_params_unexpected_fn.snap

@@ -1,15 +1,16 @@
 ---
 source: crates/cli/tests/cli_tests.rs
-assertion_line: 476
 expression: cli_dev_out.normalize_stdout_and_stderr()
+snapshot_kind: text
 ---
 
 ── TYPE MISMATCH in tests/test-projects/module_params/unexpected_fn.roc ────────
 
 This argument to this string interpolation has an unexpected type:
 
-11│      $(Api.getPost)
-           ^^^^^^^^^^^
+10│       """
+11│>      $(Api.getPost)
+12│       """
 
 The argument is an anonymous function of type:
 
@@ -21,8 +22,6 @@ But this string interpolation needs its argument to be:
 
 ────────────────────────────────────────────────────────────────────────────────
 
-1 error and 0 warning found in <ignored for test> ms
-.
+1 error and 0 warnings found in <ignored for test> ms.
 
 You can run <ignored for tests>
-

crates/compiler/can/src/constraint.rs

@@ -31,6 +31,7 @@ pub struct Constraints {
     pub cycles: Vec<Cycle>,
     pub fx_call_constraints: Vec<FxCallConstraint>,
     pub fx_suffix_constraints: Vec<FxSuffixConstraint>,
+    pub try_target_constraints: Vec<TryTargetConstraint>,
 }
 
 impl std::fmt::Debug for Constraints {
@@ -87,6 +88,7 @@ impl Constraints {
         let cycles = Vec::new();
         let fx_call_constraints = Vec::with_capacity(16);
         let fx_suffix_constraints = Vec::new();
+        let result_type_constraints = Vec::new();
 
         categories.extend([
             Category::Record,
@@ -103,7 +105,6 @@ impl Constraints {
             Category::List,
             Category::Str,
             Category::Character,
-            Category::Return,
         ]);
 
         pattern_categories.extend([
@@ -138,6 +139,7 @@ impl Constraints {
             cycles,
             fx_call_constraints,
             fx_suffix_constraints,
+            try_target_constraints: result_type_constraints,
         }
     }
 
@@ -635,6 +637,25 @@ impl Constraints {
         Constraint::FlexToPure(fx_var)
     }
 
+    pub fn try_target(
+        &mut self,
+        result_type_index: TypeOrVar,
+        ok_payload_var: Variable,
+        err_payload_var: Variable,
+        region: Region,
+    ) -> Constraint {
+        let constraint = TryTargetConstraint {
+            target_type_index: result_type_index,
+            ok_payload_var,
+            err_payload_var,
+            region,
+        };
+
+        let constraint_index = index_push_new(&mut self.try_target_constraints, constraint);
+
+        Constraint::TryTarget(constraint_index)
+    }
+
     pub fn contains_save_the_environment(&self, constraint: &Constraint) -> bool {
         match constraint {
             Constraint::SaveTheEnvironment => true,
@@ -660,6 +681,7 @@ impl Constraints {
             | Constraint::Lookup(..)
             | Constraint::Pattern(..)
             | Constraint::ExpectEffectful(..)
+            | Constraint::TryTarget(_)
             | Constraint::FxCall(_)
             | Constraint::FxSuffix(_)
             | Constraint::FlexToPure(_)
@@ -843,6 +865,8 @@ pub enum Constraint {
     FlexToPure(Variable),
     /// Expect statement or ignored def to be effectful
     ExpectEffectful(Variable, ExpectEffectfulReason, Region),
+    /// Expect value to be some kind of Result
+    TryTarget(Index<TryTargetConstraint>),
     /// Used for things that always unify, e.g. blanks and runtime errors
     True,
     SaveTheEnvironment,
@@ -909,6 +933,14 @@ pub struct IncludesTag {
     pub region: Region,
 }
 
+#[derive(Debug, Clone)]
+pub struct TryTargetConstraint {
+    pub target_type_index: TypeOrVar,
+    pub ok_payload_var: Variable,
+    pub err_payload_var: Variable,
+    pub region: Region,
+}
+
 #[derive(Debug, Clone, Copy)]
 pub struct Cycle {
     pub def_names: Slice<(Symbol, Region)>,
@@ -1000,6 +1032,9 @@ impl std::fmt::Debug for Constraint {
             Self::FlexToPure(arg0) => {
                 write!(f, "FlexToPure({arg0:?})")
             }
+            Self::TryTarget(arg0) => {
+                write!(f, "ExpectResultType({arg0:?})")
+            }
             Self::True => write!(f, "True"),
             Self::SaveTheEnvironment => write!(f, "SaveTheEnvironment"),
             Self::Let(arg0, arg1) => f.debug_tuple("Let").field(arg0).field(arg1).finish(),

crates/compiler/can/src/copy.rs

@@ -479,7 +479,7 @@ fn deep_copy_expr_help<C: CopyEnv>(env: &mut C, copied: &mut Vec<Variable>, expr
             fx_type: sub!(*fx_type),
             early_returns: early_returns
                 .iter()
-                .map(|(var, region)| (sub!(*var), *region))
+                .map(|(var, region, type_)| (sub!(*var), *region, *type_))
                 .collect(),
             name: *name,
             captured_symbols: captured_symbols
@@ -718,6 +718,22 @@ fn deep_copy_expr_help<C: CopyEnv>(env: &mut C, copied: &mut Vec<Variable>, expr
             symbol: *symbol,
         },
 
+        Try {
+            result_expr,
+            result_var,
+            return_var,
+            ok_payload_var,
+            err_payload_var,
+            err_ext_var,
+        } => Try {
+            result_expr: Box::new(result_expr.map(|e| go_help!(e))),
+            result_var: sub!(*result_var),
+            return_var: sub!(*return_var),
+            ok_payload_var: sub!(*ok_payload_var),
+            err_payload_var: sub!(*err_payload_var),
+            err_ext_var: sub!(*err_ext_var),
+        },
+
         RuntimeError(err) => RuntimeError(err.clone()),
     }
 }

crates/compiler/can/src/debug/pretty_print.rs

@@ -452,6 +452,7 @@ fn expr<'a>(c: &Ctx, p: EPrec, f: &'a Arena<'a>, e: &'a Expr) -> DocBuilder<'a,
         ),
         Dbg { .. } => todo!(),
         Expect { .. } => todo!(),
+        Try { .. } => todo!(),
         Return { .. } => todo!(),
         RuntimeError(_) => todo!(),
     }

crates/compiler/can/src/desugar.rs

@@ -44,7 +44,7 @@ fn new_op_call_expr<'a>(
             match right_without_spaces {
                 Try => {
                     let desugared_left = desugar_expr(env, scope, left);
-                    return desugar_try_expr(env, scope, desugared_left);
+                    return Loc::at(region, Expr::LowLevelTry(desugared_left));
                 }
                 Apply(&Loc { value: Try, .. }, arguments, _called_via) => {
                     let try_fn = desugar_expr(env, scope, arguments.first().unwrap());
@@ -58,13 +58,12 @@ fn new_op_call_expr<'a>(
                             .map(|a| desugar_expr(env, scope, a)),
                     );
 
-                    return desugar_try_expr(
-                        env,
-                        scope,
-                        env.arena.alloc(Loc::at(
-                            right.region,
+                    return Loc::at(
+                        region,
+                        Expr::LowLevelTry(env.arena.alloc(Loc::at(
+                            region,
                             Expr::Apply(try_fn, args.into_bump_slice(), CalledVia::Try),
-                        )),
+                        ))),
                     );
                 }
                 _ => {}
@@ -957,13 +956,17 @@ pub fn desugar_expr<'a>(
                     desugared_args.push(desugar_expr(env, scope, loc_arg));
                 }
 
+                let args_region =
+                    Region::span_across(&loc_args[0].region, &loc_args[loc_args.len() - 1].region);
+
                 env.arena.alloc(Loc::at(
-                    loc_expr.region,
+                    args_region,
                     Expr::Apply(function, desugared_args.into_bump_slice(), CalledVia::Try),
                 ))
             };
 
-            env.arena.alloc(desugar_try_expr(env, scope, result_expr))
+            env.arena
+                .alloc(Loc::at(loc_expr.region, Expr::LowLevelTry(result_expr)))
         }
         Apply(loc_fn, loc_args, called_via) => {
             let mut desugared_args = Vec::with_capacity_in(loc_args.len(), env.arena);
@@ -1134,77 +1137,11 @@ pub fn desugar_expr<'a>(
             })
         }
 
-        // note this only exists after desugaring
-        LowLevelDbg(_, _, _) => loc_expr,
+        // note these only exist after desugaring
+        LowLevelDbg(_, _, _) | LowLevelTry(_) => loc_expr,
     }
 }
 
-pub fn desugar_try_expr<'a>(
-    env: &mut Env<'a>,
-    scope: &mut Scope,
-    result_expr: &'a Loc<Expr<'a>>,
-) -> Loc<Expr<'a>> {
-    let region = result_expr.region;
-    let ok_symbol = env.arena.alloc(scope.gen_unique_symbol_name().to_string());
-    let err_symbol = env.arena.alloc(scope.gen_unique_symbol_name().to_string());
-
-    let ok_branch = env.arena.alloc(WhenBranch {
-        patterns: env.arena.alloc([Loc::at(
-            region,
-            Pattern::Apply(
-                env.arena.alloc(Loc::at(region, Pattern::Tag("Ok"))),
-                env.arena
-                    .alloc([Loc::at(region, Pattern::Identifier { ident: ok_symbol })]),
-            ),
-        )]),
-        value: Loc::at(
-            region,
-            Expr::Var {
-                module_name: "",
-                ident: ok_symbol,
-            },
-        ),
-        guard: None,
-    });
-
-    let err_branch = env.arena.alloc(WhenBranch {
-        patterns: env.arena.alloc([Loc::at(
-            region,
-            Pattern::Apply(
-                env.arena.alloc(Loc::at(region, Pattern::Tag("Err"))),
-                env.arena
-                    .alloc([Loc::at(region, Pattern::Identifier { ident: err_symbol })]),
-            ),
-        )]),
-        value: Loc::at(
-            region,
-            Expr::Return(
-                env.arena.alloc(Loc::at(
-                    region,
-                    Expr::Apply(
-                        env.arena.alloc(Loc::at(region, Expr::Tag("Err"))),
-                        &*env.arena.alloc([&*env.arena.alloc(Loc::at(
-                            region,
-                            Expr::Var {
-                                module_name: "",
-                                ident: err_symbol,
-                            },
-                        ))]),
-                        CalledVia::Try,
-                    ),
-                )),
-                None,
-            ),
-        ),
-        guard: None,
-    });
-
-    Loc::at(
-        region,
-        Expr::When(result_expr, &*env.arena.alloc([&*ok_branch, &*err_branch])),
-    )
-}
-
 fn desugar_str_segments<'a>(
     env: &mut Env<'a>,
     scope: &mut Scope,