Make unit assignment optional for suffixed defs

Cargo.lock

@@ -2531,6 +2531,7 @@ version = "0.0.1"
 dependencies = [
  "bumpalo",
  "roc_collections",
+ "roc_error_macros",
  "roc_module",
  "roc_parse",
  "roc_region",

crates/compiler/can/src/desugar.rs

@@ -1093,6 +1093,8 @@ fn desugar_pattern<'a>(
         SpaceAfter(sub_pattern, _spaces) => {
             desugar_pattern(arena, *sub_pattern, src, line_info, module_path)
         }
+
+        Stmt(_) => unreachable!("should have been handled in the parser"),
     }
 }
 

crates/compiler/can/src/pattern.rs

@@ -6,6 +6,7 @@ use crate::num::{
     ParsedNumResult,
 };
 use crate::scope::{PendingAbilitiesInScope, Scope};
+use roc_error_macros::internal_error;
 use roc_exhaustive::ListArity;
 use roc_module::ident::{Ident, Lowercase, TagName};
 use roc_module::symbol::Symbol;
@@ -882,6 +883,8 @@ pub fn canonicalize_pattern<'a>(
             let problem = MalformedPatternProblem::QualifiedIdentifier;
             malformed_pattern(env, problem, region)
         }
+
+        Stmt(_) => internal_error!("should have been handled in the parser"),
     };
 
     Loc {

crates/compiler/fmt/Cargo.toml

@@ -12,5 +12,6 @@ roc_collections = { path = "../collections" }
 roc_module = { path = "../module" }
 roc_parse = { path = "../parse" }
 roc_region = { path = "../region" }
+roc_error_macros = { path = "../../error_macros" }
 
 bumpalo.workspace = true

crates/compiler/fmt/src/def.rs

@@ -357,9 +357,19 @@ pub fn fmt_defs(buf: &mut Buf, defs: &Defs, indent: u16) {
 }
 
 pub fn fmt_body<'a>(buf: &mut Buf, pattern: &'a Pattern<'a>, body: &'a Expr<'a>, indent: u16) {
-    pattern.format_with_options(buf, Parens::InApply, Newlines::No, indent);
-    buf.indent(indent);
-    buf.push_str(" =");
+    // Check if this is an assignment into the unit/empty record, format as a Statement
+    let is_statement = if let Pattern::RecordDestructure(collection) = pattern {
+        collection.is_empty()
+    } else {
+        false
+    };
+
+    // Don't format the `{} =` for defs with this pattern
+    if !is_statement {
+        pattern.format_with_options(buf, Parens::InApply, Newlines::No, indent);
+        buf.indent(indent);
+        buf.push_str(" =");
+    }
 
     if body.is_multiline() {
         match body {

crates/compiler/fmt/src/pattern.rs

@@ -2,6 +2,7 @@ use crate::annotation::{Formattable, Newlines, Parens};
 use crate::expr::{fmt_str_literal, format_sq_literal};
 use crate::spaces::{fmt_comments_only, fmt_spaces, NewlineAt, INDENT};
 use crate::Buf;
+use roc_error_macros::internal_error;
 use roc_parse::ast::{Base, CommentOrNewline, Pattern, PatternAs};
 
 pub fn fmt_pattern<'a>(buf: &mut Buf, pattern: &'a Pattern<'a>, indent: u16, parens: Parens) {
@@ -81,6 +82,7 @@ impl<'a> Formattable for Pattern<'a> {
             Pattern::Tuple(patterns) | Pattern::List(patterns) => {
                 patterns.iter().any(|p| p.is_multiline())
             }
+            Pattern::Stmt(_) => true,
         }
     }
 
@@ -279,6 +281,10 @@ impl<'a> Formattable for Pattern<'a> {
 
                 buf.push_str(ident);
             }
+
+            // Statement e.g. Suffixed with optional `{}=`
+            // e.g. `Stdout.line! "Hello World"`
+            Stmt(_) => internal_error!("should be desugared in parser into alternate pattern"),
         }
     }
 }

crates/compiler/fmt/src/spaces.rs

@@ -837,6 +837,7 @@ impl<'a> RemoveSpaces<'a> for Pattern<'a> {
                 opt_pattern_as
                     .map(|(_, pattern_as)| ([].as_ref(), pattern_as.remove_spaces(arena))),
             ),
+            Pattern::Stmt(a) => Pattern::Stmt(a),
         }
     }
 }

crates/compiler/parse/src/ast.rs

@@ -872,6 +872,10 @@ impl<'a> PatternAs<'a> {
 pub enum Pattern<'a> {
     // Identifier
     Identifier(&'a str),
+    QualifiedIdentifier {
+        module_name: &'a str,
+        ident: &'a str,
+    },
 
     Tag(&'a str),
 
@@ -923,10 +927,9 @@ pub enum Pattern<'a> {
     // Malformed
     Malformed(&'a str),
     MalformedIdent(&'a str, crate::ident::BadIdent),
-    QualifiedIdentifier {
-        module_name: &'a str,
-        ident: &'a str,
-    },
+
+    // Statement e.g. `Stdout.line! "Hello"`
+    Stmt(&'a str),
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
@@ -1126,6 +1129,8 @@ impl<'a> Pattern<'a> {
                     false
                 }
             }
+
+            Stmt(_) => todo!(),
         }
     }
 }
@@ -1773,6 +1778,8 @@ impl<'a> Malformed for Pattern<'a> {
             Malformed(_) |
             MalformedIdent(_, _) |
             QualifiedIdentifier { .. } => true,
+
+            Stmt(_) => todo!(),
         }
     }
 }

crates/compiler/parse/src/expr.rs

@@ -626,6 +626,40 @@ pub fn parse_single_def<'a>(
             // a hacky way to get expression-based error messages. TODO fix this
             Ok((NoProgress, None, initial))
         }
+        // Check if we have a Statement with Suffixed first,
+        // re-parse the state as an expression
+        // and then use a `{}=` pattern for the ValueDef::Body.
+        Ok((
+            MadeProgress,
+            Loc {
+                region,
+                value: Pattern::Stmt(_),
+                ..
+            },
+            _,
+        )) => {
+            let parse_def_expr =
+                space0_before_e(increment_min_indent(expr_start(options)), EExpr::IndentEnd);
+
+            let (_, loc_def_expr, updated_state) =
+                parse_def_expr.parse(arena, state, min_indent)?;
+
+            let loc_pattern = Loc::at(region, Pattern::RecordDestructure(Collection::empty()));
+
+            let value_def = ValueDef::Body(arena.alloc(loc_pattern), &*arena.alloc(loc_def_expr));
+
+            let region = Region::span_across(&loc_pattern.region, &loc_def_expr.region);
+
+            Ok((
+                MadeProgress,
+                Some(SingleDef {
+                    type_or_value: Either::Second(value_def),
+                    region,
+                    spaces_before: spaces_before_current,
+                }),
+                updated_state,
+            ))
+        }
         Ok((_, loc_pattern, state)) => {
             // First let's check whether this is an ability definition.
             let opt_tag_and_args: Option<(&str, Region, &[Loc<Pattern>])> = match loc_pattern.value

crates/compiler/parse/src/pattern.rs

@@ -12,6 +12,7 @@ use crate::string_literal::StrLikeLiteral;
 use bumpalo::collections::string::String;
 use bumpalo::collections::Vec;
 use bumpalo::Bump;
+use roc_error_macros::internal_error;
 use roc_region::all::{Loc, Region};
 
 /// Different patterns are supported in different circumstances.
@@ -49,6 +50,11 @@ pub fn loc_pattern_help<'a>() -> impl Parser<'a, Loc<Pattern<'a>>, EPattern<'a>>
 
         let pattern_state = state.clone();
 
+        // Return early with the suffixed statement
+        if let Pattern::Stmt(_) = pattern.value {
+            return Ok((MadeProgress, pattern, pattern_state));
+        }
+
         let (pattern_spaces, state) =
             match space0_e(EPattern::AsKeyword).parse(arena, state, min_indent) {
                 Err(_) => return Ok((MadeProgress, pattern, pattern_state)),
@@ -385,6 +391,39 @@ fn loc_ident_pattern_help<'a>(
                     Ok((MadeProgress, loc_pat, state))
                 }
             }
+            // Parse a statement that begins with a suffixed identifier, e.g. `Stdout.line! "Hello"`
+            Ident::Access {
+                module_name,
+                parts,
+                suffixed,
+                ..
+            } if suffixed => {
+                if module_name.is_empty() && parts.len() == 1 {
+                    if let Accessor::RecordField(var) = &parts[0] {
+                        return Ok((
+                            MadeProgress,
+                            Loc {
+                                region: loc_ident.region,
+                                value: Pattern::Stmt(var),
+                            },
+                            state,
+                        ));
+                    } else {
+                        internal_error!("unexpected suffixed TupleIndex");
+                    }
+                } else if let Accessor::RecordField(var) = &parts[0] {
+                    return Ok((
+                        MadeProgress,
+                        Loc {
+                            region: loc_ident.region,
+                            value: Pattern::Stmt(arena.alloc(format!("{}.{}", module_name, var))),
+                        },
+                        state,
+                    ));
+                } else {
+                    internal_error!("unexpected suffixed TupleIndex");
+                }
+            }
             Ident::Access {
                 module_name, parts, ..
             } => {

crates/compiler/test_syntax/tests/snapshots/pass/suffixed_def_optional_bang.moduledefs.formatted.roc

@@ -0,0 +1,2 @@
+A.x! "Foo" []
+B.y! "Bar" \a -> x + y

crates/compiler/test_syntax/tests/snapshots/pass/suffixed_def_optional_bang.moduledefs.result-ast

@@ -0,0 +1,91 @@
+Defs {
+    tags: [
+        Index(2147483648),
+        Index(2147483649),
+    ],
+    regions: [
+        @0-19,
+        @20-45,
+    ],
+    space_before: [
+        Slice(start = 0, length = 0),
+        Slice(start = 0, length = 1),
+    ],
+    space_after: [
+        Slice(start = 0, length = 0),
+        Slice(start = 1, length = 0),
+    ],
+    spaces: [
+        Newline,
+    ],
+    type_defs: [],
+    value_defs: [
+        Body(
+            @0-4 RecordDestructure(
+                [],
+            ),
+            @0-19 Apply(
+                @0-4 Suffixed(
+                    Var {
+                        module_name: "A",
+                        ident: "x",
+                    },
+                ),
+                [
+                    @8-13 Str(
+                        PlainLine(
+                            "Foo",
+                        ),
+                    ),
+                    @17-19 List(
+                        [],
+                    ),
+                ],
+                Space,
+            ),
+        ),
+        Body(
+            @20-24 RecordDestructure(
+                [],
+            ),
+            @20-45 Apply(
+                @20-24 Suffixed(
+                    Var {
+                        module_name: "B",
+                        ident: "y",
+                    },
+                ),
+                [
+                    @27-32 Str(
+                        PlainLine(
+                            "Bar",
+                        ),
+                    ),
+                    @34-45 Closure(
+                        [
+                            @35-36 Identifier(
+                                "a",
+                            ),
+                        ],
+                        @40-45 BinOps(
+                            [
+                                (
+                                    @40-41 Var {
+                                        module_name: "",
+                                        ident: "x",
+                                    },
+                                    @42-43 Plus,
+                                ),
+                            ],
+                            @44-45 Var {
+                                module_name: "",
+                                ident: "y",
+                            },
+                        ),
+                    ),
+                ],
+                Space,
+            ),
+        ),
+    ],
+}

crates/compiler/test_syntax/tests/snapshots/pass/suffixed_def_optional_bang.moduledefs.roc

@@ -0,0 +1,2 @@
+A.x!    "Foo"    []
+B.y!   "Bar"  \a -> x + y

crates/compiler/test_syntax/tests/test_snapshots.rs

@@ -442,6 +442,7 @@ mod test_snapshots {
         pass/sub_var_with_spaces.expr,
         pass/sub_with_spaces.expr,
         pass/suffixed.expr,
+        pass/suffixed_def_optional_bang.moduledefs,
         pass/suffixed_nested.expr,
         pass/tag_pattern.expr,
         pass/ten_times_eleven.expr,

crates/lang_srv/src/analysis/tokens.rs

@@ -777,6 +777,7 @@ impl IterTokens for Loc<Pattern<'_>> {
             }
             Pattern::QualifiedIdentifier { .. } => onetoken(Token::Variable, region, arena),
             Pattern::Malformed(_) | Pattern::MalformedIdent(_, _) => bumpvec![in arena;],
+            Pattern::Stmt(_) => onetoken(Token::Operator, region, arena),
         }
     }
 }