Merge branch 'trunk' into edit_big_string

Cargo.lock

@@ -3060,6 +3060,7 @@ dependencies = [
  "roc_reporting",
  "roc_solve",
  "roc_types",
+ "roc_unify",
  "ropey",
  "serde",
  "snafu",

compiler/can/src/expected.rs

@@ -89,4 +89,16 @@ impl<T> Expected<T> {
             }
         }
     }
+
+    pub fn replace_ref<U>(&self, new: U) -> Expected<U> {
+        match self {
+            Expected::NoExpectation(_val) => Expected::NoExpectation(new),
+            Expected::ForReason(reason, _val, region) => {
+                Expected::ForReason(reason.clone(), new, *region)
+            }
+            Expected::FromAnnotation(pattern, size, source, _val) => {
+                Expected::FromAnnotation(pattern.clone(), *size, *source, new)
+            }
+        }
+    }
 }

compiler/can/src/expr.rs

@@ -409,6 +409,18 @@ pub fn canonicalize_expr<'a>(
         ast::Expr::Var { module_name, ident } => {
             canonicalize_lookup(env, scope, module_name, ident, region)
         }
+        ast::Expr::Underscore(name) => {
+            // we parse underscores, but they are not valid expression syntax
+            let problem = roc_problem::can::RuntimeError::MalformedIdentifier(
+                (*name).into(),
+                roc_parse::ident::BadIdent::Underscore(region.start_line, region.start_col),
+                region,
+            );
+
+            env.problem(Problem::RuntimeError(problem.clone()));
+
+            (RuntimeError(problem), Output::default())
+        }
         ast::Expr::Defs(loc_defs, loc_ret) => {
             can_defs_with_return(
                 env,

compiler/can/src/operator.rs

@@ -119,6 +119,7 @@ pub fn desugar_expr<'a>(arena: &'a Bump, loc_expr: &'a Located<Expr<'a>>) -> &'a
         | Str(_)
         | AccessorFunction(_)
         | Var { .. }
+        | Underscore { .. }
         | MalformedIdent(_, _)
         | MalformedClosure
         | PrecedenceConflict { .. }

compiler/can/src/pattern.rs

@@ -198,7 +198,7 @@ pub fn canonicalize_pattern<'a>(
 
         Underscore(_) => match pattern_type {
             WhenBranch | FunctionArg => Pattern::Underscore,
-            ptype => unsupported_pattern(env, ptype, region),
+            TopLevelDef | DefExpr => bad_underscore(env, region),
         },
 
         NumLiteral(string) => match pattern_type {
@@ -402,7 +402,21 @@ pub fn canonicalize_pattern<'a>(
 /// When we detect an unsupported pattern type (e.g. 5 = 1 + 2 is unsupported because you can't
 /// assign to Int patterns), report it to Env and return an UnsupportedPattern runtime error pattern.
 fn unsupported_pattern(env: &mut Env, pattern_type: PatternType, region: Region) -> Pattern {
-    env.problem(Problem::UnsupportedPattern(pattern_type, region));
+    use roc_problem::can::BadPattern;
+    env.problem(Problem::UnsupportedPattern(
+        BadPattern::Unsupported(pattern_type),
+        region,
+    ));
+
+    Pattern::UnsupportedPattern(region)
+}
+
+fn bad_underscore(env: &mut Env, region: Region) -> Pattern {
+    use roc_problem::can::BadPattern;
+    env.problem(Problem::UnsupportedPattern(
+        BadPattern::UnderscoreInDef,
+        region,
+    ));
 
     Pattern::UnsupportedPattern(region)
 }

compiler/fmt/src/expr.rs

@@ -30,6 +30,7 @@ impl<'a> Formattable<'a> for Expr<'a> {
             | Access(_, _)
             | AccessorFunction(_)
             | Var { .. }
+            | Underscore { .. }
             | MalformedIdent(_, _)
             | MalformedClosure
             | GlobalTag(_)
@@ -189,6 +190,10 @@ impl<'a> Formattable<'a> for Expr<'a> {
 
                 buf.push_str(ident);
             }
+            Underscore(name) => {
+                buf.push('_');
+                buf.push_str(name);
+            }
             Apply(loc_expr, loc_args, _) => {
                 if apply_needs_parens {
                     buf.push('(');

compiler/parse/src/ast.rs

@@ -115,6 +115,8 @@ pub enum Expr<'a> {
         ident: &'a str,
     },
 
+    Underscore(&'a str),
+
     // Tags
     GlobalTag(&'a str),
     PrivateTag(&'a str),

compiler/parse/src/expr.rs

@@ -192,6 +192,30 @@ fn record_field_access<'a>() -> impl Parser<'a, &'a str, EExpr<'a>> {
     )
 }
 
+/// In some contexts we want to parse the `_` as an expression, so it can then be turned into a
+/// pattern later
+fn parse_loc_term_or_underscore<'a>(
+    min_indent: u16,
+    options: ExprParseOptions,
+    arena: &'a Bump,
+    state: State<'a>,
+) -> ParseResult<'a, Located<Expr<'a>>, EExpr<'a>> {
+    one_of!(
+        loc_expr_in_parens_etc_help(min_indent),
+        loc!(specialize(EExpr::Str, string_literal_help())),
+        loc!(specialize(EExpr::Number, positive_number_literal_help())),
+        loc!(specialize(EExpr::Lambda, closure_help(min_indent, options))),
+        loc!(underscore_expression()),
+        loc!(record_literal_help(min_indent)),
+        loc!(specialize(EExpr::List, list_literal_help(min_indent))),
+        loc!(map_with_arena!(
+            assign_or_destructure_identifier(),
+            ident_to_expr
+        )),
+    )
+    .parse(arena, state)
+}
+
 fn parse_loc_term<'a>(
     min_indent: u16,
     options: ExprParseOptions,
@@ -213,6 +237,26 @@ fn parse_loc_term<'a>(
     .parse(arena, state)
 }
 
+fn underscore_expression<'a>() -> impl Parser<'a, Expr<'a>, EExpr<'a>> {
+    move |arena: &'a Bump, state: State<'a>| {
+        let (_, _, next_state) = word1(b'_', EExpr::Underscore).parse(arena, state)?;
+
+        let lowercase_ident_expr = {
+            let row = state.line;
+            let col = state.column;
+
+            specialize(move |_, _, _| EExpr::End(row, col), lowercase_ident())
+        };
+
+        let (_, output, final_state) = optional(lowercase_ident_expr).parse(arena, next_state)?;
+
+        match output {
+            Some(name) => Ok((MadeProgress, Expr::Underscore(name), final_state)),
+            None => Ok((MadeProgress, Expr::Underscore(&""), final_state)),
+        }
+    }
+}
+
 fn loc_possibly_negative_or_negated_term<'a>(
     min_indent: u16,
     options: ExprParseOptions,
@@ -243,10 +287,7 @@ fn loc_possibly_negative_or_negated_term<'a>(
                 )
             }
         )),
-        |arena, state| {
-            // TODO use parse_loc_term_better
-            parse_loc_term(min_indent, options, arena, state)
-        }
+        |arena, state| { parse_loc_term_or_underscore(min_indent, options, arena, state) }
     ]
 }
 
@@ -1316,6 +1357,7 @@ fn expr_to_pattern_help<'a>(arena: &'a Bump, expr: &Expr<'a>) -> Result<Pattern<
                 Ok(Pattern::QualifiedIdentifier { module_name, ident })
             }
         }
+        Expr::Underscore(opt_name) => Ok(Pattern::Underscore(opt_name)),
         Expr::GlobalTag(value) => Ok(Pattern::GlobalTag(value)),
         Expr::PrivateTag(value) => Ok(Pattern::PrivateTag(value)),
         Expr::Apply(loc_val, loc_args, _) => {

compiler/parse/src/parser.rs

@@ -411,6 +411,7 @@ pub enum EExpr<'a> {
     If(If<'a>, Row, Col),
 
     Lambda(ELambda<'a>, Row, Col),
+    Underscore(Row, Col),
 
     InParens(EInParens<'a>, Row, Col),
     Record(ERecord<'a>, Row, Col),

compiler/parse/tests/test_parse.rs

@@ -1573,7 +1573,7 @@ mod test_parse {
     #[test]
     fn single_underscore_closure() {
         let arena = Bump::new();
-        let pattern = Located::new(0, 0, 1, 2, Underscore(&""));
+        let pattern = Located::new(0, 0, 1, 2, Pattern::Underscore(&""));
         let patterns = &[pattern];
         let expected = Closure(patterns, arena.alloc(Located::new(0, 0, 6, 8, Num("42"))));
         let actual = parse_expr_with(&arena, "\\_ -> 42");
@@ -1635,8 +1635,8 @@ mod test_parse {
     #[test]
     fn closure_with_underscores() {
         let arena = Bump::new();
-        let underscore1 = Located::new(0, 0, 1, 2, Underscore(&""));
-        let underscore2 = Located::new(0, 0, 4, 9, Underscore(&"name"));
+        let underscore1 = Located::new(0, 0, 1, 2, Pattern::Underscore(&""));
+        let underscore2 = Located::new(0, 0, 4, 9, Pattern::Underscore(&"name"));
         let patterns = bumpalo::vec![in &arena; underscore1, underscore2];
         let expected = Closure(
             arena.alloc(patterns),
@@ -1866,6 +1866,49 @@ mod test_parse {
         );
     }
 
+    #[test]
+    fn underscore_backpassing() {
+        let arena = Bump::new();
+        let newlines = bumpalo::vec![in &arena; Newline, Newline];
+        let underscore = Located::new(1, 1, 0, 1, Pattern::Underscore(&""));
+        let identifier_y = Located::new(1, 1, 7, 8, Identifier("y"));
+
+        let num_4 = Num("4");
+
+        let var_y = Var {
+            module_name: "",
+            ident: "y",
+        };
+        let loc_var_y = arena.alloc(Located::new(1, 1, 12, 13, var_y));
+
+        let closure = ParensAround(arena.alloc(Closure(arena.alloc([identifier_y]), loc_var_y)));
+        let loc_closure = Located::new(1, 1, 5, 14, closure);
+
+        let ret = Expr::SpaceBefore(arena.alloc(num_4), newlines.into_bump_slice());
+        let loc_ret = Located::new(3, 3, 0, 1, ret);
+
+        let reset_indentation = bumpalo::vec![in &arena; LineComment(" leading comment")];
+        let expected = Expr::SpaceBefore(
+            arena.alloc(Expr::Backpassing(
+                arena.alloc([underscore]),
+                arena.alloc(loc_closure),
+                arena.alloc(loc_ret),
+            )),
+            reset_indentation.into_bump_slice(),
+        );
+
+        assert_parses_to(
+            indoc!(
+                r#"# leading comment
+                _ <- (\y -> y)
+
+                4
+                "#
+            ),
+            expected,
+        );
+    }
+
     #[test]
     fn two_backpassing() {
         let arena = Bump::new();
@@ -2624,7 +2667,7 @@ mod test_parse {
             guard: None,
         });
         let newlines = &[Newline];
-        let pattern2 = Pattern::SpaceBefore(arena.alloc(Underscore("")), newlines);
+        let pattern2 = Pattern::SpaceBefore(arena.alloc(Pattern::Underscore("")), newlines);
         let loc_pattern2 = Located::new(3, 3, 4, 5, pattern2);
         let expr2 = Num("4");
         let loc_expr2 = Located::new(3, 3, 9, 10, expr2);
@@ -2661,7 +2704,7 @@ mod test_parse {
 
         let branch1 = {
             let newlines = &[Newline];
-            let pattern1 = Pattern::SpaceBefore(arena.alloc(Underscore("")), newlines);
+            let pattern1 = Pattern::SpaceBefore(arena.alloc(Pattern::Underscore("")), newlines);
             let loc_pattern1 = Located::new(1, 1, 4, 5, pattern1);
             let num_1 = Num("1");
             let expr1 = Located::new(
@@ -2680,7 +2723,8 @@ mod test_parse {
         };
 
         let branch2 = {
-            let pattern1 = Pattern::SpaceBefore(arena.alloc(Underscore("")), &[Newline, Newline]);
+            let pattern1 =
+                Pattern::SpaceBefore(arena.alloc(Pattern::Underscore("")), &[Newline, Newline]);
             let loc_pattern1 = Located::new(4, 4, 4, 5, pattern1);
             let num_1 = Num("2");
             let expr1 = Located::new(
@@ -3576,7 +3620,7 @@ mod test_parse {
             guard: None,
         });
         let newlines = &[Newline];
-        let pattern2 = Pattern::SpaceBefore(arena.alloc(Underscore(&"")), newlines);
+        let pattern2 = Pattern::SpaceBefore(arena.alloc(Pattern::Underscore(&"")), newlines);
         let loc_pattern2 = Located::new(2, 2, 4, 5, pattern2);
         let expr2 = Num("4");
         let loc_expr2 = Located::new(2, 2, 9, 10, expr2);
@@ -3621,7 +3665,7 @@ mod test_parse {
             guard: None,
         });
         let newlines = &[Newline];
-        let pattern2 = Pattern::SpaceBefore(arena.alloc(Underscore(&"")), newlines);
+        let pattern2 = Pattern::SpaceBefore(arena.alloc(Pattern::Underscore(&"")), newlines);
         let loc_pattern2 = Located::new(2, 2, 4, 5, pattern2);
         let expr2 = Num("4");
         let loc_expr2 = Located::new(2, 2, 9, 10, expr2);

compiler/problem/src/can.rs

@@ -14,6 +14,12 @@ pub struct CycleEntry {
     pub expr_region: Region,
 }
 
+#[derive(Clone, Debug, PartialEq)]
+pub enum BadPattern {
+    UnderscoreInDef,
+    Unsupported(PatternType),
+}
+
 /// Problems that can occur in the course of canonicalization.
 #[derive(Clone, Debug, PartialEq)]
 pub enum Problem {
@@ -25,7 +31,7 @@ pub enum Problem {
     UnusedArgument(Symbol, Symbol, Region),
     PrecedenceProblem(PrecedenceProblem),
     // Example: (5 = 1 + 2) is an unsupported pattern in an assignment; Int patterns aren't allowed in assignments!
-    UnsupportedPattern(PatternType, Region),
+    UnsupportedPattern(BadPattern, Region),
     ShadowingInAnnotation {
         original_region: Region,
         shadow: Located<Ident>,

compiler/reporting/src/error/canonicalize.rs

@@ -2,7 +2,7 @@ use roc_collections::all::MutSet;
 use roc_module::ident::Lowercase;
 use roc_parse::parser::{Col, Row};
 use roc_problem::can::PrecedenceProblem::BothNonAssociative;
-use roc_problem::can::{FloatErrorKind, IntErrorKind, Problem, RuntimeError};
+use roc_problem::can::{BadPattern, FloatErrorKind, IntErrorKind, Problem, RuntimeError};
 use roc_region::all::Region;
 use std::path::PathBuf;
 
@@ -103,7 +103,11 @@ pub fn can_problem<'b>(
                 },
                 alloc.region(region),
             ]),
-        Problem::UnsupportedPattern(pattern_type, region) => {
+        Problem::UnsupportedPattern(BadPattern::UnderscoreInDef, region) => alloc.stack(vec![
+            alloc.reflow("Underscore patterns are not allowed in definitions"),
+            alloc.region(region),
+        ]),
+        Problem::UnsupportedPattern(BadPattern::Unsupported(pattern_type), region) => {
             use roc_parse::pattern::PatternType::*;
 
             let this_thing = match pattern_type {

compiler/reporting/tests/test_reporting.rs

@@ -6334,4 +6334,27 @@ mod test_reporting {
             ),
         )
     }
+
+    #[test]
+    fn underscore_let() {
+        report_problem_as(
+            indoc!(
+                r#"
+                _ = 3
+
+                4
+                "#
+            ),
+            indoc!(
+                r#"
+                ── SYNTAX PROBLEM ──────────────────────────────────────────────────────────────
+                
+                Underscore patterns are not allowed in definitions
+                
+                1│  _ = 3
+                    ^
+            "#
+            ),
+        )
+    }
 }

compiler/types/src/types.rs

@@ -858,7 +858,7 @@ pub enum PReason {
     OptionalField,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum AnnotationSource {
     TypedIfBranch { index: Index, num_branches: usize },
     TypedWhenBranch { index: Index },

editor/Cargo.toml

@@ -15,6 +15,7 @@ roc_region = { path = "../compiler/region" }
 roc_module = { path = "../compiler/module" }
 roc_problem = { path = "../compiler/problem" }
 roc_types = { path = "../compiler/types" }
+roc_unify = { path = "../compiler/unify" }
 roc_fmt = { path = "../compiler/fmt" }
 roc_reporting = { path = "../compiler/reporting" }
 roc_solve = { path = "../compiler/solve" }

editor/src/lang/mod.rs

@@ -7,4 +7,5 @@ mod pattern;
 pub mod pool;
 pub mod roc_file;
 pub mod scope;
+pub mod solve;
 pub mod types;

editor/src/lang/pattern.rs

@@ -153,7 +153,7 @@ pub fn to_pattern2<'a>(
 
         Underscore(_) => match pattern_type {
             WhenBranch | FunctionArg => Pattern2::Underscore,
-            ptype => unsupported_pattern(env, ptype, region),
+            TopLevelDef | DefExpr => underscore_in_def(env, region),
         },
 
         FloatLiteral(ref string) => match pattern_type {
@@ -521,7 +521,21 @@ fn unsupported_pattern<'a>(
     pattern_type: PatternType,
     region: Region,
 ) -> Pattern2 {
-    env.problem(Problem::UnsupportedPattern(pattern_type, region));
+    use roc_problem::can::BadPattern;
+    env.problem(Problem::UnsupportedPattern(
+        BadPattern::Unsupported(pattern_type),
+        region,
+    ));
+
+    Pattern2::UnsupportedPattern(region)
+}
+
+fn underscore_in_def<'a>(env: &mut Env<'a>, region: Region) -> Pattern2 {
+    use roc_problem::can::BadPattern;
+    env.problem(Problem::UnsupportedPattern(
+        BadPattern::UnderscoreInDef,
+        region,
+    ));
 
     Pattern2::UnsupportedPattern(region)
 }

editor/tests/solve_expr2.rs

@@ -5,45 +5,50 @@ extern crate indoc;
 
 use bumpalo::Bump;
 use roc_can::expected::Expected;
+use roc_collections::all::MutMap;
+use roc_editor::lang::solve;
 use roc_editor::lang::{
     constrain::constrain_expr,
+    constrain::Constraint,
     expr::{str_to_expr2, Env},
     pool::Pool,
     scope::Scope,
     types::Type2,
 };
+use roc_module::ident::Lowercase;
+use roc_module::symbol::Symbol;
 use roc_module::symbol::{IdentIds, ModuleIds};
 use roc_region::all::Region;
-use roc_solve::module::run_solve;
-use roc_types::{pretty_print::content_to_string, subs::VarStore, types::Type};
+use roc_types::solved_types::Solved;
+use roc_types::subs::{Subs, Variable};
+use roc_types::{pretty_print::content_to_string, subs::VarStore};
 
-fn ed_constraint_to_can_constraint(
-    constraint: roc_editor::lang::constrain::Constraint,
-) -> roc_can::constraint::Constraint {
-    match constraint {
-        roc_editor::lang::constrain::Constraint::Eq(typ, expected, category, region) => {
-            let new_typ = type2_to_type(&typ);
-            let expected_typ = expected.get_type_ref();
+fn run_solve(
+    mempool: &mut Pool,
+    aliases: MutMap<Symbol, roc_types::types::Alias>,
+    rigid_variables: MutMap<Variable, Lowercase>,
+    constraint: Constraint,
+    var_store: VarStore,
+) -> (Solved<Subs>, solve::Env, Vec<solve::TypeError>) {
+    let env = solve::Env {
+        vars_by_symbol: MutMap::default(),
+        aliases,
+    };
 
-            let expected_typ = type2_to_type(expected_typ);
+    let mut subs = Subs::new(var_store.into());
 
-            roc_can::constraint::Constraint::Eq(
-                new_typ,
-                expected.replace(expected_typ),
-                category,
-                region,
-            )
-        }
-        _ => todo!("{:?}", constraint),
+    for (var, name) in rigid_variables {
+        subs.rigid_var(var, name);
     }
-}
 
-fn type2_to_type(typ: &Type2) -> Type {
-    match typ {
-        Type2::Apply(symbol, _) => Type::Apply(*symbol, Vec::new()),
-        Type2::Variable(var) => Type::Variable(*var),
-        _ => todo!("{:?}", typ),
-    }
+    // Now that the module is parsed, canonicalized, and constrained,
+    // we need to type check it.
+    let mut problems = Vec::new();
+
+    // Run the solver to populate Subs.
+    let (solved_subs, solved_env) = solve::run(mempool, &env, &mut problems, subs, &constraint);
+
+    (solved_subs, solved_env, problems)
 }
 
 fn infer_eq(actual: &str, expected_str: &str) {
@@ -83,20 +88,29 @@ fn infer_eq(actual: &str, expected_str: &str) {
                 Expected::NoExpectation(Type2::Variable(var)),
             );
 
-            let constraint = ed_constraint_to_can_constraint(constraint);
+            let Env {
+                pool,
+                var_store: ref_var_store,
+                ..
+            } = env;
+
+            // extract the var_store out of the env again
+            let mut var_store = VarStore::default();
+            std::mem::swap(ref_var_store, &mut var_store);
 
             let (mut solved, _, _) = run_solve(
+                pool,
                 Default::default(),
                 Default::default(),
                 constraint,
                 var_store,
             );
 
-            let mut subs = solved.inner_mut();
+            let subs = solved.inner_mut();
 
             let content = subs.get(var).content;
 
-            let actual_str = content_to_string(content, &mut subs, mod_id, &Default::default());
+            let actual_str = content_to_string(content, &subs, mod_id, &Default::default());
 
             assert_eq!(actual_str, expected_str);
         }

examples/cli/HttpGet.roc

@@ -5,7 +5,7 @@ app "http-get"
 
 main : Task.Task {} *
 main =
-    {} <- await (Stdout.line "What URL should I get?")
+    _ <- await (Stdout.line "What URL should I get?")
 
     url <- await Stdin.line