Merge remote-tracking branch 'origin/trunk' into recursive-tag-segfault

cli/src/repl.rs

@@ -296,7 +296,7 @@ fn gen(src: &[u8], target: Triple, opt_level: OptLevel) -> Result<ReplOutput, Fa
             exposed_to_host: MutSet::default(),
         };
 
-        let mut layout_ids = roc_gen::layout_id::LayoutIds::default();
+        let mut layout_ids = roc_mono::layout::LayoutIds::default();
         let mut headers = Vec::with_capacity(procedures.len());
 
         // Add all the Proc headers to the module.

cli/tests/repl_eval.rs

@@ -261,6 +261,13 @@ mod repl_eval {
         expect_success("List.contains [ 1, 2, 3 ] 4", "False : Bool");
     }
 
+    #[test]
+    fn list_sum() {
+        expect_success("List.sum []", "0 : Num *");
+        expect_success("List.sum [ 1, 2, 3 ]", "6 : Num *");
+        expect_success("List.sum [ 1.1, 2.2, 3.3 ]", "6.6 : Float");
+    }
+
     #[test]
     fn empty_record() {
         expect_success("{}", "{} : {}");

compiler/build/src/link.rs

@@ -263,6 +263,7 @@ fn link_macos(
             .args(&[
                 // Libraries - see https://github.com/rtfeldman/roc/pull/554#discussion_r496392274
                 // for discussion and further references
+                "-L/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/lib",
                 "-lSystem",
                 "-lresolv",
                 "-lpthread",

compiler/build/src/program.rs

@@ -2,9 +2,9 @@ use crate::target;
 use bumpalo::Bump;
 use inkwell::context::Context;
 use inkwell::targets::{CodeModel, FileType, RelocMode};
-use roc_gen::layout_id::LayoutIds;
 use roc_gen::llvm::build::{build_proc, build_proc_header, module_from_builtins, OptLevel, Scope};
 use roc_load::file::MonomorphizedModule;
+use roc_mono::layout::LayoutIds;
 use std::path::{Path, PathBuf};
 use target_lexicon::Triple;
 

compiler/builtins/src/std.rs

@@ -474,6 +474,15 @@ pub fn types() -> MutMap<Symbol, (SolvedType, Region)> {
         ),
     );
 
+    // sum :  List (Num a) -> Num a
+    add_type(
+        Symbol::LIST_SUM,
+        top_level_function(
+            vec![list_type(num_type(flex(TVAR1)))],
+            Box::new(num_type(flex(TVAR1))),
+        ),
+    );
+
     // walkRight : List elem, (elem -> accum -> accum), accum -> accum
     add_type(
         Symbol::LIST_WALK_RIGHT,

compiler/builtins/src/unique.rs

@@ -683,6 +683,23 @@ pub fn types() -> MutMap<Symbol, (SolvedType, Region)> {
         unique_function(vec![list_type(star1, a), flex(a)], bool_type(star2))
     });
 
+    // sum : Attr * (List (Attr u (Num (Attr u num))))
+    //     -> Attr v (Num (Attr v num))
+    add_type(Symbol::LIST_SUM, {
+        let_tvars! { star1, u, v, num };
+
+        unique_function(
+            vec![SolvedType::Apply(
+                Symbol::ATTR_ATTR,
+                vec![
+                    flex(star1),
+                    SolvedType::Apply(Symbol::LIST_LIST, vec![num_type(u, num)]),
+                ],
+            )],
+            num_type(v, num),
+        )
+    });
+
     // join : Attr * (List (Attr * (List a)))
     //     -> Attr * (List a)
     add_type(Symbol::LIST_JOIN, {

compiler/can/src/builtins.rs

@@ -65,6 +65,7 @@ pub fn builtin_defs(var_store: &mut VarStore) -> MutMap<Symbol, Def> {
         Symbol::LIST_REVERSE => list_reverse,
         Symbol::LIST_CONCAT => list_concat,
         Symbol::LIST_CONTAINS => list_contains,
+        Symbol::LIST_SUM => list_sum,
         Symbol::LIST_PREPEND => list_prepend,
         Symbol::LIST_JOIN => list_join,
         Symbol::LIST_MAP => list_map,
@@ -1320,6 +1321,26 @@ fn list_walk_right(symbol: Symbol, var_store: &mut VarStore) -> Def {
     )
 }
 
+/// List.sum : List (Num a) -> Num a
+fn list_sum(symbol: Symbol, var_store: &mut VarStore) -> Def {
+    let list_var = var_store.fresh();
+    let result_var = var_store.fresh();
+
+    let body = RunLowLevel {
+        op: LowLevel::ListSum,
+        args: vec![(list_var, Var(Symbol::ARG_1))],
+        ret_var: result_var,
+    };
+
+    defn(
+        symbol,
+        vec![(list_var, Symbol::ARG_1)],
+        var_store,
+        body,
+        result_var,
+    )
+}
+
 /// List.keepIf : List elem, (elem -> Bool) -> List elem
 fn list_keep_if(symbol: Symbol, var_store: &mut VarStore) -> Def {
     let list_var = var_store.fresh();

compiler/fmt/src/annotation.rs

@@ -1,4 +1,4 @@
-use crate::spaces::{fmt_comments_only, fmt_condition_spaces, fmt_spaces, newline, INDENT};
+use crate::spaces::{fmt_comments_only, fmt_spaces, newline, NewlineAt, INDENT};
 use bumpalo::collections::String;
 use roc_parse::ast::{AssignedField, Expr, Tag, TypeAnnotation};
 use roc_region::all::Located;
@@ -333,7 +333,7 @@ fn format_assigned_field_help<'a, T>(
             buf.push_str(name.value);
         }
         AssignedField::SpaceBefore(sub_field, spaces) => {
-            fmt_comments_only(buf, spaces.iter(), indent);
+            fmt_comments_only(buf, spaces.iter(), NewlineAt::Bottom, indent);
             format_assigned_field_help(
                 sub_field,
                 buf,
@@ -352,7 +352,7 @@ fn format_assigned_field_help<'a, T>(
                 separator_prefix,
                 is_multiline,
             );
-            fmt_comments_only(buf, spaces.iter(), indent);
+            fmt_comments_only(buf, spaces.iter(), NewlineAt::Bottom, indent);
         }
         Malformed(raw) => {
             buf.push_str(raw);
@@ -448,7 +448,12 @@ macro_rules! implement_format_sequence {
                     match &item.value {
                         $t::SpaceBefore(expr_below, spaces_above_expr) => {
                             newline(buf, item_indent);
-                            fmt_comments_only(buf, spaces_above_expr.iter(), item_indent);
+                            fmt_comments_only(
+                                buf,
+                                spaces_above_expr.iter(),
+                                NewlineAt::Bottom,
+                                item_indent,
+                            );
 
                             match &expr_below {
                                 $t::SpaceAfter(expr_above, spaces_below_expr) => {
@@ -458,9 +463,10 @@ macro_rules! implement_format_sequence {
                                         buf.push(',');
                                     }
 
-                                    fmt_condition_spaces(
+                                    fmt_comments_only(
                                         buf,
                                         spaces_below_expr.iter(),
+                                        NewlineAt::Top,
                                         item_indent,
                                     );
                                 }
@@ -481,7 +487,7 @@ macro_rules! implement_format_sequence {
                                 buf.push(',');
                             }
 
-                            fmt_condition_spaces(buf, spaces.iter(), item_indent);
+                            fmt_comments_only(buf, spaces.iter(), NewlineAt::Top, item_indent);
                         }
 
                         _ => {

compiler/fmt/src/def.rs

@@ -1,6 +1,6 @@
 use crate::annotation::{Formattable, Newlines, Parens};
 use crate::pattern::fmt_pattern;
-use crate::spaces::{fmt_spaces, is_comment, newline, INDENT};
+use crate::spaces::{fmt_spaces, newline, INDENT};
 use bumpalo::collections::String;
 use roc_parse::ast::{Def, Expr, Pattern};
 
@@ -17,7 +17,7 @@ impl<'a> Formattable<'a> for Def<'a> {
             Body(loc_pattern, loc_expr) => loc_pattern.is_multiline() || loc_expr.is_multiline(),
             AnnotatedBody { .. } => true,
             SpaceBefore(sub_def, spaces) | SpaceAfter(sub_def, spaces) => {
-                spaces.iter().any(|s| is_comment(s)) || sub_def.is_multiline()
+                spaces.iter().any(|s| s.is_comment()) || sub_def.is_multiline()
             }
             Nested(def) => def.is_multiline(),
             NotYetImplemented(s) => todo!("{}", s),

compiler/fmt/src/expr.rs

@@ -1,9 +1,7 @@
 use crate::annotation::{Formattable, Newlines, Parens};
 use crate::def::fmt_def;
 use crate::pattern::fmt_pattern;
-use crate::spaces::{
+use crate::spaces::{add_spaces, fmt_comments_only, fmt_spaces, newline, NewlineAt, INDENT};
-    add_spaces, fmt_comments_only, fmt_condition_spaces, fmt_spaces, newline, INDENT,
-};
 use bumpalo::collections::String;
 use roc_module::operator::{self, BinOp};
 use roc_parse::ast::StrSegment;
@@ -108,7 +106,7 @@ impl<'a> Formattable<'a> for Expr<'a> {
                 if format_newlines {
                     fmt_spaces(buf, spaces.iter(), indent);
                 } else {
-                    fmt_comments_only(buf, spaces.iter(), indent);
+                    fmt_comments_only(buf, spaces.iter(), NewlineAt::Bottom, indent);
                 }
                 sub_expr.format_with_options(buf, parens, newlines, indent);
             }
@@ -117,7 +115,7 @@ impl<'a> Formattable<'a> for Expr<'a> {
                 if format_newlines {
                     fmt_spaces(buf, spaces.iter(), indent);
                 } else {
-                    fmt_comments_only(buf, spaces.iter(), indent);
+                    fmt_comments_only(buf, spaces.iter(), NewlineAt::Bottom, indent);
                 }
             }
             ParensAround(sub_expr) => {
@@ -416,7 +414,12 @@ pub fn fmt_list<'a>(buf: &mut String<'a>, loc_items: &[&Located<Expr<'a>>], inde
             match &item.value {
                 Expr::SpaceBefore(expr_below, spaces_above_expr) => {
                     newline(buf, item_indent);
-                    fmt_comments_only(buf, spaces_above_expr.iter(), item_indent);
+                    fmt_comments_only(
+                        buf,
+                        spaces_above_expr.iter(),
+                        NewlineAt::Bottom,
+                        item_indent,
+                    );
 
                     match &expr_below {
                         Expr::SpaceAfter(expr_above, spaces_below_expr) => {
@@ -426,7 +429,12 @@ pub fn fmt_list<'a>(buf: &mut String<'a>, loc_items: &[&Located<Expr<'a>>], inde
                                 buf.push(',');
                             }
 
-                            fmt_condition_spaces(buf, spaces_below_expr.iter(), item_indent);
+                            fmt_comments_only(
+                                buf,
+                                spaces_below_expr.iter(),
+                                NewlineAt::Top,
+                                item_indent,
+                            );
                         }
                         _ => {
                             expr_below.format(buf, item_indent);
@@ -446,7 +454,7 @@ pub fn fmt_list<'a>(buf: &mut String<'a>, loc_items: &[&Located<Expr<'a>>], inde
                         buf.push(',');
                     }
 
-                    fmt_condition_spaces(buf, spaces.iter(), item_indent);
+                    fmt_comments_only(buf, spaces.iter(), NewlineAt::Top, item_indent);
                 }
 
                 _ => {
@@ -521,12 +529,22 @@ fn fmt_when<'a>(
 
         match &loc_condition.value {
             Expr::SpaceBefore(expr_below, spaces_above_expr) => {
-                fmt_condition_spaces(buf, spaces_above_expr.iter(), condition_indent);
+                fmt_comments_only(
+                    buf,
+                    spaces_above_expr.iter(),
+                    NewlineAt::Top,
+                    condition_indent,
+                );
                 newline(buf, condition_indent);
                 match &expr_below {
                     Expr::SpaceAfter(expr_above, spaces_below_expr) => {
                         expr_above.format(buf, condition_indent);
-                        fmt_condition_spaces(buf, spaces_below_expr.iter(), condition_indent);
+                        fmt_comments_only(
+                            buf,
+                            spaces_below_expr.iter(),
+                            NewlineAt::Top,
+                            condition_indent,
+                        );
                         newline(buf, indent);
                     }
                     _ => {
@@ -585,7 +603,7 @@ fn fmt_when<'a>(
         add_spaces(buf, indent + (INDENT * 2));
         match expr.value {
             Expr::SpaceBefore(nested, spaces) => {
-                fmt_comments_only(buf, spaces.iter(), indent + (INDENT * 2));
+                fmt_comments_only(buf, spaces.iter(), NewlineAt::Bottom, indent + (INDENT * 2));
                 nested.format_with_options(
                     buf,
                     Parens::NotNeeded,
@@ -633,13 +651,18 @@ fn fmt_if<'a>(
     if is_multiline_condition {
         match &loc_condition.value {
             Expr::SpaceBefore(expr_below, spaces_above_expr) => {
-                fmt_condition_spaces(buf, spaces_above_expr.iter(), return_indent);
+                fmt_comments_only(buf, spaces_above_expr.iter(), NewlineAt::Top, return_indent);
                 newline(buf, return_indent);
 
                 match &expr_below {
                     Expr::SpaceAfter(expr_above, spaces_below_expr) => {
                         expr_above.format(buf, return_indent);
-                        fmt_condition_spaces(buf, spaces_below_expr.iter(), return_indent);
+                        fmt_comments_only(
+                            buf,
+                            spaces_below_expr.iter(),
+                            NewlineAt::Top,
+                            return_indent,
+                        );
                         newline(buf, indent);
                     }
 
@@ -652,7 +675,7 @@ fn fmt_if<'a>(
             Expr::SpaceAfter(expr_above, spaces_below_expr) => {
                 newline(buf, return_indent);
                 expr_above.format(buf, return_indent);
-                fmt_condition_spaces(buf, spaces_below_expr.iter(), return_indent);
+                fmt_comments_only(buf, spaces_below_expr.iter(), NewlineAt::Top, return_indent);
                 newline(buf, indent);
             }
 
@@ -675,13 +698,13 @@ fn fmt_if<'a>(
             Expr::SpaceBefore(expr_below, spaces_below) => {
                 // we want exactly one newline, user-inserted extra newlines are ignored.
                 newline(buf, return_indent);
-                fmt_comments_only(buf, spaces_below.iter(), return_indent);
+                fmt_comments_only(buf, spaces_below.iter(), NewlineAt::Bottom, return_indent);
 
                 match &expr_below {
                     Expr::SpaceAfter(expr_above, spaces_above) => {
                         expr_above.format(buf, return_indent);
 
-                        fmt_condition_spaces(buf, spaces_above.iter(), return_indent);
+                        fmt_comments_only(buf, spaces_above.iter(), NewlineAt::Top, return_indent);
                         newline(buf, indent);
                     }
 
@@ -783,7 +806,7 @@ pub fn fmt_record<'a>(
     buf: &mut String<'a>,
     update: Option<&'a Located<Expr<'a>>>,
     loc_fields: &[Located<AssignedField<'a, Expr<'a>>>],
-    final_comments: &[CommentOrNewline<'a>],
+    final_comments: &'a [CommentOrNewline<'a>],
     indent: u16,
 ) {
     if loc_fields.is_empty() {
@@ -810,12 +833,14 @@ pub fn fmt_record<'a>(
         if is_multiline {
             let field_indent = indent + INDENT;
             for field in loc_fields.iter() {
-                field.format_with_options(buf, Parens::NotNeeded, Newlines::Yes, field_indent);
+                format_field_multiline(buf, &field.value, field_indent, "");
-                buf.push(',');
             }
+
+            fmt_comments_only(buf, final_comments.iter(), NewlineAt::Top, field_indent);
+
             newline(buf, indent);
         } else {
-            // is_multiline == false
+            // is_multiline == false */
             buf.push(' ');
             let field_indent = indent;
             let mut iter = loc_fields.iter().peekable();
@@ -827,7 +852,67 @@ pub fn fmt_record<'a>(
                 }
             }
             buf.push(' ');
+            // if we are here, that means that `final_comments` is empty, thus we don't have
+            // to add a comment. Anyway, it is not possible to have a single line record with
+            // a comment in it.
         };
+
+        // closes the initial bracket
         buf.push('}');
     }
 }
+
+fn format_field_multiline<'a, T>(
+    buf: &mut String<'a>,
+    field: &AssignedField<'a, T>,
+    indent: u16,
+    separator_prefix: &str,
+) where
+    T: Formattable<'a>,
+{
+    use self::AssignedField::*;
+    match field {
+        RequiredValue(name, spaces, ann) => {
+            newline(buf, indent);
+            buf.push_str(name.value);
+
+            if !spaces.is_empty() {
+                fmt_spaces(buf, spaces.iter(), indent);
+            }
+
+            buf.push_str(separator_prefix);
+            buf.push_str(": ");
+            ann.value.format(buf, indent);
+            buf.push(',');
+        }
+        OptionalValue(name, spaces, ann) => {
+            newline(buf, indent);
+            buf.push_str(name.value);
+
+            if !spaces.is_empty() {
+                fmt_spaces(buf, spaces.iter(), indent);
+            }
+
+            buf.push_str(separator_prefix);
+            buf.push('?');
+            ann.value.format(buf, indent);
+            buf.push(',');
+        }
+        LabelOnly(name) => {
+            newline(buf, indent);
+            buf.push_str(name.value);
+            buf.push(',');
+        }
+        AssignedField::SpaceBefore(sub_field, spaces) => {
+            fmt_comments_only(buf, spaces.iter(), NewlineAt::Top, indent);
+            format_field_multiline(buf, sub_field, indent, separator_prefix);
+        }
+        AssignedField::SpaceAfter(sub_field, spaces) => {
+            format_field_multiline(buf, sub_field, indent, separator_prefix);
+            fmt_comments_only(buf, spaces.iter(), NewlineAt::Top, indent);
+        }
+        Malformed(raw) => {
+            buf.push_str(raw);
+        }
+    }
+}

compiler/fmt/src/pattern.rs

@@ -1,5 +1,5 @@
 use crate::annotation::{Formattable, Newlines, Parens};
-use crate::spaces::{fmt_comments_only, fmt_spaces, is_comment};
+use crate::spaces::{fmt_comments_only, fmt_spaces, NewlineAt};
 use bumpalo::collections::String;
 use roc_parse::ast::{Base, Pattern};
 
@@ -19,7 +19,7 @@ impl<'a> Formattable<'a> for Pattern<'a> {
             Pattern::SpaceBefore(_, spaces) | Pattern::SpaceAfter(_, spaces) => {
                 debug_assert!(!spaces.is_empty());
 
-                spaces.iter().any(|s| is_comment(s))
+                spaces.iter().any(|s| s.is_comment())
             }
 
             Pattern::Nested(nested_pat) => nested_pat.is_multiline(),
@@ -133,7 +133,7 @@ impl<'a> Formattable<'a> for Pattern<'a> {
             // Space
             SpaceBefore(sub_pattern, spaces) => {
                 if !sub_pattern.is_multiline() {
-                    fmt_comments_only(buf, spaces.iter(), indent)
+                    fmt_comments_only(buf, spaces.iter(), NewlineAt::Bottom, indent)
                 } else {
                     fmt_spaces(buf, spaces.iter(), indent);
                 }
@@ -143,7 +143,7 @@ impl<'a> Formattable<'a> for Pattern<'a> {
                 sub_pattern.format_with_options(buf, parens, newlines, indent);
                 // if only_comments {
                 if !sub_pattern.is_multiline() {
-                    fmt_comments_only(buf, spaces.iter(), indent)
+                    fmt_comments_only(buf, spaces.iter(), NewlineAt::Bottom, indent)
                 } else {
                     fmt_spaces(buf, spaces.iter(), indent);
                 }

compiler/fmt/src/spaces.rs

@@ -45,12 +45,14 @@ where
                 }
             }
             LineComment(comment) => {
-                fmt_comment(buf, comment, indent);
+                fmt_comment(buf, comment);
+                newline(buf, indent);
 
                 encountered_comment = true;
             }
             DocComment(docs) => {
-                fmt_docs(buf, docs, indent);
+                fmt_docs(buf, docs);
+                newline(buf, indent);
 
                 encountered_comment = true;
             }
@@ -58,78 +60,67 @@ where
     }
 }
 
-/// Similar to fmt_comments_only, but does not finish with a newline()
+#[derive(Eq, PartialEq, Debug)]
-/// Used to format when and if statement conditions
+pub enum NewlineAt {
-pub fn fmt_condition_spaces<'a, I>(buf: &mut String<'a>, spaces: I, indent: u16)
+    Top,
-where
+    Bottom,
-    I: Iterator<Item = &'a CommentOrNewline<'a>>,
+    Both,
-{
+    None,
-    use self::CommentOrNewline::*;
-
-    let mut iter = spaces.peekable();
-
-    while let Some(space) = iter.next() {
-        match space {
-            Newline => {}
-            LineComment(comment) => {
-                buf.push('#');
-                buf.push_str(comment);
-            }
-            DocComment(docs) => {
-                buf.push_str("##");
-                buf.push_str(docs);
-            }
-        }
-        match iter.peek() {
-            None => {}
-            Some(next_space) => match next_space {
-                Newline => {}
-                LineComment(_) | DocComment(_) => {
-                    newline(buf, indent);
-                }
-            },
-        }
-    }
 }
 
 /// Like format_spaces, but remove newlines and keep only comments.
-pub fn fmt_comments_only<'a, I>(buf: &mut String<'a>, spaces: I, indent: u16)
+/// The `new_line_at` argument describes how new lines should be inserted
-where
+/// at the beginning or at the end of the block
+/// in the case of there is some comment in the `spaces` argument.
+pub fn fmt_comments_only<'a, I>(
+    buf: &mut String<'a>,
+    spaces: I,
+    new_line_at: NewlineAt,
+    indent: u16,
+) where
     I: Iterator<Item = &'a CommentOrNewline<'a>>,
 {
     use self::CommentOrNewline::*;
+    use NewlineAt::*;
+
+    let mut comment_seen = false;
 
     for space in spaces {
         match space {
             Newline => {}
             LineComment(comment) => {
-                fmt_comment(buf, comment, indent);
+                if comment_seen || new_line_at == Top || new_line_at == Both {
+                    newline(buf, indent);
+                }
+                fmt_comment(buf, comment);
+                comment_seen = true;
             }
             DocComment(docs) => {
-                fmt_docs(buf, docs, indent);
+                if comment_seen || new_line_at == Top || new_line_at == Both {
+                    newline(buf, indent);
+                }
+                fmt_docs(buf, docs);
+                comment_seen = true;
             }
         }
     }
+    if comment_seen && (new_line_at == Bottom || new_line_at == Both) {
+        newline(buf, indent);
+    }
 }
 
-fn fmt_comment<'a>(buf: &mut String<'a>, comment: &'a str, indent: u16) {
+fn fmt_comment<'a>(buf: &mut String<'a>, comment: &'a str) {
     buf.push('#');
-    buf.push_str(comment);
+    if !comment.starts_with(' ') {
-
+        buf.push(' ');
-    newline(buf, indent);
-}
-
-fn fmt_docs<'a>(buf: &mut String<'a>, docs: &'a str, indent: u16) {
-    buf.push_str("##");
-    buf.push_str(docs);
-
-    newline(buf, indent);
-}
-
-pub fn is_comment<'a>(space: &'a CommentOrNewline<'a>) -> bool {
-    match space {
-        CommentOrNewline::Newline => false,
-        CommentOrNewline::LineComment(_) => true,
-        CommentOrNewline::DocComment(_) => true,
     }
+    buf.push_str(comment);
+}
+
+fn fmt_docs<'a>(buf: &mut String<'a>, docs: &'a str) {
+    buf.push_str("##");
+    if !docs.starts_with(' ') {
+        buf.push(' ');
+    }
+    buf.push_str(docs);
 }

compiler/fmt/tests/test_fmt.rs

@@ -129,6 +129,24 @@ mod test_fmt {
         );
     }
 
+    #[test]
+    fn force_space_at_begining_of_comment() {
+        expr_formats_to(
+            indoc!(
+                r#"
+                #comment
+                f
+                "#
+            ),
+            indoc!(
+                r#"
+                # comment
+                f
+                "#
+            ),
+        );
+    }
+
     #[test]
     fn func_def() {
         expr_formats_same(indoc!(
@@ -616,6 +634,129 @@ mod test_fmt {
         );
     }
 
+    #[test]
+    fn final_comments_in_records() {
+        expr_formats_same(indoc!(
+            r#"
+            {
+                x: 42,
+                # comment
+            }"#
+        ));
+
+        expr_formats_same(indoc!(
+            r#"
+            {
+                x: 42,
+                # comment
+                # other comment
+            }"#
+        ));
+    }
+
+    #[test]
+    fn final_comments_without_comma_in_records() {
+        expr_formats_to(
+            indoc!(
+                r#"
+            {
+                y: 41,
+                # comment 1
+                x: 42 # comment 2
+            }"#
+            ),
+            indoc!(
+                r#"
+            {
+                y: 41,
+                # comment 1
+                x: 42,
+                # comment 2
+            }"#
+            ),
+        );
+    }
+
+    #[test]
+    fn multiple_final_comments_without_comma_in_records() {
+        expr_formats_to(
+            indoc!(
+                r#"
+            {
+                y: 41,
+                x: 42 # comment 1
+                # comment 2
+            }"#
+            ),
+            indoc!(
+                r#"
+            {
+                y: 41,
+                x: 42,
+                # comment 1
+                # comment 2
+            }"#
+            ),
+        );
+    }
+
+    #[test]
+    fn comments_with_newlines_in_records() {
+        expr_formats_to(
+            indoc!(
+                r#"
+            {
+                z: 44 #comment 0
+                ,
+                y: 41, # comment 1
+
+                # comment 2
+                x: 42
+                
+                # comment 3
+                
+                # comment 4
+            }"#
+            ),
+            indoc!(
+                r#"
+            {
+                z: 44,
+                # comment 0
+                y: 41,
+                # comment 1
+                # comment 2
+                x: 42,
+                # comment 3
+                # comment 4
+            }"#
+            ),
+        );
+    }
+
+    #[test]
+    fn multiple_final_comments_with_comma_in_records() {
+        expr_formats_to(
+            indoc!(
+                r#"
+            {
+                y: 41,
+                x: 42, # comment 1
+                # comment 2
+            }"#
+            ),
+            indoc!(
+                r#"
+            {
+                y: 41,
+                x: 42,
+                # comment 1
+                # comment 2
+            }"#
+            ),
+        );
+    }
+
     #[test]
     fn def_closure() {
         expr_formats_same(indoc!(

compiler/gen/src/layout_id.rs

@@ -1,53 +0,0 @@
-use roc_collections::all::{default_hasher, MutMap};
-use roc_module::symbol::{Interns, Symbol};
-use roc_mono::layout::Layout;
-use std::collections::HashMap;
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub struct LayoutId(u32);
-
-impl LayoutId {
-    // Returns something like "foo#1" when given a symbol that interns to "foo"
-    // and a LayoutId of 1.
-    pub fn to_symbol_string(self, symbol: Symbol, interns: &Interns) -> String {
-        let ident_string = symbol.ident_string(interns);
-        let module_string = interns.module_ids.get_name(symbol.module_id()).unwrap();
-        format!("{}_{}_{}", module_string, ident_string, self.0)
-    }
-}
-
-struct IdsByLayout<'a> {
-    by_id: MutMap<Layout<'a>, u32>,
-    next_id: u32,
-}
-
-#[derive(Default)]
-pub struct LayoutIds<'a> {
-    by_symbol: MutMap<Symbol, IdsByLayout<'a>>,
-}
-
-impl<'a> LayoutIds<'a> {
-    /// Returns a LayoutId which is unique for the given symbol and layout.
-    /// If given the same symbol and same layout, returns the same LayoutId.
-    pub fn get(&mut self, symbol: Symbol, layout: &Layout<'a>) -> LayoutId {
-        // Note: this function does some weird stuff to satisfy the borrow checker.
-        // There's probably a nicer way to write it that still works.
-        let ids = self.by_symbol.entry(symbol).or_insert_with(|| IdsByLayout {
-            by_id: HashMap::with_capacity_and_hasher(1, default_hasher()),
-            next_id: 1,
-        });
-
-        // Get the id associated with this layout, or default to next_id.
-        let answer = ids.by_id.get(layout).copied().unwrap_or(ids.next_id);
-
-        // If we had to default to next_id, it must not have been found;
-        // store the ID we're going to return and increment next_id.
-        if answer == ids.next_id {
-            ids.by_id.insert(layout.clone(), ids.next_id);
-
-            ids.next_id += 1;
-        }
-
-        LayoutId(answer)
-    }
-}

compiler/gen/src/lib.rs

@@ -11,7 +11,6 @@
 // re-enable this when working on performance optimizations than have it block PRs.
 #![allow(clippy::large_enum_variant)]
 
-pub mod layout_id;
 pub mod llvm;
 
 pub mod run_roc;

compiler/gen/src/llvm/build.rs

@@ -1,8 +1,7 @@
-use crate::layout_id::LayoutIds;
 use crate::llvm::build_list::{
     allocate_list, empty_list, empty_polymorphic_list, list_append, list_concat, list_contains,
     list_get_unsafe, list_join, list_keep_if, list_len, list_map, list_prepend, list_repeat,
-    list_reverse, list_set, list_single, list_walk_right,
+    list_reverse, list_set, list_single, list_sum, list_walk_right,
 };
 use crate::llvm::build_str::{str_concat, str_count_graphemes, str_len, str_split, CHAR_LAYOUT};
 use crate::llvm::compare::{build_eq, build_neq};
@@ -34,7 +33,7 @@ use roc_collections::all::{ImMap, MutSet};
 use roc_module::low_level::LowLevel;
 use roc_module::symbol::{Interns, ModuleId, Symbol};
 use roc_mono::ir::{JoinPointId, Wrapped};
-use roc_mono::layout::{Builtin, ClosureLayout, Layout, MemoryMode};
+use roc_mono::layout::{Builtin, ClosureLayout, Layout, LayoutIds, MemoryMode};
 use target_lexicon::CallingConvention;
 
 /// This is for Inkwell's FunctionValue::verify - we want to know the verification
@@ -2362,6 +2361,13 @@ fn run_low_level<'a, 'ctx, 'env>(
                 default_layout,
             )
         }
+        ListSum => {
+            debug_assert_eq!(args.len(), 1);
+
+            let list = load_symbol(env, scope, &args[0]);
+
+            list_sum(env, parent, list, layout)
+        }
         ListAppend => {
             // List.append : List elem, elem -> List elem
             debug_assert_eq!(args.len(), 2);
@@ -2512,40 +2518,7 @@ fn run_low_level<'a, 'ctx, 'env>(
             let (lhs_arg, lhs_layout) = load_symbol_and_layout(env, scope, &args[0]);
             let (rhs_arg, rhs_layout) = load_symbol_and_layout(env, scope, &args[1]);
 
-            match (lhs_layout, rhs_layout) {
+            build_num_binop(env, parent, lhs_arg, lhs_layout, rhs_arg, rhs_layout, op)
-                (Layout::Builtin(lhs_builtin), Layout::Builtin(rhs_builtin))
-                    if lhs_builtin == rhs_builtin =>
-                {
-                    use roc_mono::layout::Builtin::*;
-
-                    match lhs_builtin {
-                        Int128 | Int64 | Int32 | Int16 | Int8 => build_int_binop(
-                            env,
-                            parent,
-                            lhs_arg.into_int_value(),
-                            lhs_layout,
-                            rhs_arg.into_int_value(),
-                            rhs_layout,
-                            op,
-                        ),
-                        Float128 | Float64 | Float32 | Float16 => build_float_binop(
-                            env,
-                            parent,
-                            lhs_arg.into_float_value(),
-                            lhs_layout,
-                            rhs_arg.into_float_value(),
-                            rhs_layout,
-                            op,
-                        ),
-                        _ => {
-                            unreachable!("Compiler bug: tried to run numeric operation {:?} on invalid builtin layout: ({:?})", op, lhs_layout);
-                        }
-                    }
-                }
-                _ => {
-                    unreachable!("Compiler bug: tried to run numeric operation {:?} on invalid layouts. The 2 layouts were: ({:?}) and ({:?})", op, lhs_layout, rhs_layout);
-                }
-            }
         }
         Eq => {
             debug_assert_eq!(args.len(), 2);
@@ -2797,14 +2770,57 @@ fn call_bitcode_fn_help<'a, 'ctx, 'env>(
         .get_function(fn_name)
         .unwrap_or_else(|| panic!("Unrecognized builtin function: {:?} - if you're working on the Roc compiler, do you need to rebuild the bitcode? See compiler/builtins/bitcode/README.md", fn_name));
 
-    dbg!(fn_val);
-
     let call = env.builder.build_call(fn_val, args, "call_builtin");
 
     call.set_call_convention(fn_val.get_call_conventions());
     call
 }
 
+pub fn build_num_binop<'a, 'ctx, 'env>(
+    env: &Env<'a, 'ctx, 'env>,
+    parent: FunctionValue<'ctx>,
+    lhs_arg: BasicValueEnum<'ctx>,
+    lhs_layout: &Layout<'a>,
+    rhs_arg: BasicValueEnum<'ctx>,
+    rhs_layout: &Layout<'a>,
+    op: LowLevel,
+) -> BasicValueEnum<'ctx> {
+    match (lhs_layout, rhs_layout) {
+        (Layout::Builtin(lhs_builtin), Layout::Builtin(rhs_builtin))
+            if lhs_builtin == rhs_builtin =>
+        {
+            use roc_mono::layout::Builtin::*;
+
+            match lhs_builtin {
+                Int128 | Int64 | Int32 | Int16 | Int8 => build_int_binop(
+                    env,
+                    parent,
+                    lhs_arg.into_int_value(),
+                    lhs_layout,
+                    rhs_arg.into_int_value(),
+                    rhs_layout,
+                    op,
+                ),
+                Float128 | Float64 | Float32 | Float16 => build_float_binop(
+                    env,
+                    parent,
+                    lhs_arg.into_float_value(),
+                    lhs_layout,
+                    rhs_arg.into_float_value(),
+                    rhs_layout,
+                    op,
+                ),
+                _ => {
+                    unreachable!("Compiler bug: tried to run numeric operation {:?} on invalid builtin layout: ({:?})", op, lhs_layout);
+                }
+            }
+        }
+        _ => {
+            unreachable!("Compiler bug: tried to run numeric operation {:?} on invalid layouts. The 2 layouts were: ({:?}) and ({:?})", op, lhs_layout, rhs_layout);
+        }
+    }
+}
+
 fn build_float_binop<'a, 'ctx, 'env>(
     env: &Env<'a, 'ctx, 'env>,
     parent: FunctionValue<'ctx>,

compiler/gen/src/llvm/build_list.rs

@@ -1,4 +1,4 @@
-use crate::llvm::build::{Env, InPlace};
+use crate::llvm::build::{build_num_binop, Env, InPlace};
 use crate::llvm::compare::build_eq;
 use crate::llvm::convert::{basic_type_from_layout, collection, get_ptr_type, ptr_int};
 use inkwell::builder::Builder;
@@ -728,6 +728,81 @@ pub fn list_len<'ctx>(
         .into_int_value()
 }
 
+/// List.sum : List (Num a) -> Num a
+pub fn list_sum<'a, 'ctx, 'env>(
+    env: &Env<'a, 'ctx, 'env>,
+    parent: FunctionValue<'ctx>,
+    list: BasicValueEnum<'ctx>,
+    default_layout: &Layout<'a>,
+) -> BasicValueEnum<'ctx> {
+    let ctx = env.context;
+    let builder = env.builder;
+
+    let list_wrapper = list.into_struct_value();
+    let len = list_len(env.builder, list_wrapper);
+
+    let accum_type = basic_type_from_layout(env.arena, ctx, default_layout, env.ptr_bytes);
+    let accum_alloca = builder.build_alloca(accum_type, "alloca_walk_right_accum");
+
+    let default: BasicValueEnum = match accum_type {
+        BasicTypeEnum::IntType(int_type) => int_type.const_zero().into(),
+        BasicTypeEnum::FloatType(float_type) => float_type.const_zero().into(),
+        _ => unreachable!(""),
+    };
+
+    builder.build_store(accum_alloca, default);
+
+    let then_block = ctx.append_basic_block(parent, "then");
+    let cont_block = ctx.append_basic_block(parent, "branchcont");
+
+    let condition = builder.build_int_compare(
+        IntPredicate::UGT,
+        len,
+        ctx.i64_type().const_zero(),
+        "list_non_empty",
+    );
+
+    builder.build_conditional_branch(condition, then_block, cont_block);
+
+    builder.position_at_end(then_block);
+
+    let elem_ptr_type = get_ptr_type(&accum_type, AddressSpace::Generic);
+    let list_ptr = load_list_ptr(builder, list_wrapper, elem_ptr_type);
+
+    let walk_right_loop = |_, elem: BasicValueEnum<'ctx>| {
+        // load current accumulator
+        let current = builder.build_load(accum_alloca, "retrieve_accum");
+
+        let new_current = build_num_binop(
+            env,
+            parent,
+            current,
+            default_layout,
+            elem,
+            default_layout,
+            roc_module::low_level::LowLevel::NumAdd,
+        );
+
+        builder.build_store(accum_alloca, new_current);
+    };
+
+    incrementing_elem_loop(
+        builder,
+        ctx,
+        parent,
+        list_ptr,
+        len,
+        "#index",
+        walk_right_loop,
+    );
+
+    builder.build_unconditional_branch(cont_block);
+
+    builder.position_at_end(cont_block);
+
+    builder.build_load(accum_alloca, "load_final_acum")
+}
+
 /// List.walkRight : List elem, (elem -> accum -> accum), accum -> accum
 #[allow(clippy::too_many_arguments)]
 pub fn list_walk_right<'a, 'ctx, 'env>(

compiler/gen/src/llvm/refcounting.rs

@@ -1,4 +1,3 @@
-use crate::layout_id::LayoutIds;
 use crate::llvm::build::{
     cast_basic_basic, cast_struct_struct, create_entry_block_alloca, set_name, Env, Scope,
     FAST_CALL_CONV, LLVM_SADD_WITH_OVERFLOW_I64,
@@ -12,7 +11,7 @@ use inkwell::module::Linkage;
 use inkwell::values::{BasicValueEnum, FunctionValue, IntValue, PointerValue, StructValue};
 use inkwell::{AddressSpace, IntPredicate};
 use roc_module::symbol::Symbol;
-use roc_mono::layout::{Builtin, Layout, MemoryMode};
+use roc_mono::layout::{Builtin, Layout, LayoutIds, MemoryMode};
 
 pub const REFCOUNT_MAX: usize = 0 as usize;
 

compiler/gen/tests/gen_list.rs

@@ -1612,4 +1612,11 @@ mod gen_list {
 
         assert_evals_to!(indoc!("List.contains [] 4"), false, bool);
     }
+
+    #[test]
+    fn list_sum() {
+        assert_evals_to!("List.sum []", 0, i64);
+        assert_evals_to!("List.sum [ 1, 2, 3 ]", 6, i64);
+        assert_evals_to!("List.sum [ 1.1, 2.2, 3.3 ]", 6.6, f64);
+    }
 }

compiler/gen/tests/helpers/eval.rs

@@ -165,7 +165,7 @@ pub fn helper<'a>(
         exposed_to_host: MutSet::default(),
     };
 
-    let mut layout_ids = roc_gen::layout_id::LayoutIds::default();
+    let mut layout_ids = roc_mono::layout::LayoutIds::default();
     let mut headers = Vec::with_capacity(procedures.len());
 
     // Add all the Proc headers to the module.

compiler/module/src/low_level.rs

@@ -22,6 +22,7 @@ pub enum LowLevel {
     ListMap,
     ListKeepIf,
     ListWalkRight,
+    ListSum,
     NumAdd,
     NumAddWrap,
     NumAddChecked,

compiler/module/src/symbol.rs

@@ -693,6 +693,7 @@ define_builtins! {
         16 LIST_JOIN: "join"
         17 LIST_KEEP_IF: "keepIf"
         18 LIST_CONTAINS: "contains"
+        19 LIST_SUM: "sum"
     }
     5 RESULT: "Result" => {
         0 RESULT_RESULT: "Result" imported // the Result.Result type alias

compiler/mono/src/borrow.rs

@@ -536,6 +536,7 @@ pub fn lowlevel_borrow_signature(arena: &Bump, op: LowLevel) -> &[bool] {
         ListKeepIf => arena.alloc_slice_copy(&[owned, irrelevant]),
         ListContains => arena.alloc_slice_copy(&[borrowed, irrelevant]),
         ListWalkRight => arena.alloc_slice_copy(&[borrowed, irrelevant, owned]),
+        ListSum => arena.alloc_slice_copy(&[borrowed]),
 
         Eq | NotEq | And | Or | NumAdd | NumAddWrap | NumAddChecked | NumSub | NumMul | NumGt
         | NumGte | NumLt | NumLte | NumCompare | NumDivUnchecked | NumRemUnchecked | NumPow

compiler/mono/src/layout.rs

@@ -1,9 +1,10 @@
 use bumpalo::collections::Vec;
 use bumpalo::Bump;
-use roc_collections::all::{MutMap, MutSet};
+use roc_collections::all::{default_hasher, MutMap, MutSet};
 use roc_module::ident::{Lowercase, TagName};
-use roc_module::symbol::Symbol;
+use roc_module::symbol::{Interns, Symbol};
 use roc_types::subs::{Content, FlatType, Subs, Variable};
+use std::collections::HashMap;
 
 pub const MAX_ENUM_SIZE: usize = (std::mem::size_of::<u8>() * 8) as usize;
 
@@ -1298,3 +1299,52 @@ pub fn mode_from_var(var: Variable, subs: &Subs) -> MemoryMode {
         _ => MemoryMode::Refcounted,
     }
 }
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct LayoutId(u32);
+
+impl LayoutId {
+    // Returns something like "foo#1" when given a symbol that interns to "foo"
+    // and a LayoutId of 1.
+    pub fn to_symbol_string(self, symbol: Symbol, interns: &Interns) -> String {
+        let ident_string = symbol.ident_string(interns);
+        let module_string = interns.module_ids.get_name(symbol.module_id()).unwrap();
+        format!("{}_{}_{}", module_string, ident_string, self.0)
+    }
+}
+
+struct IdsByLayout<'a> {
+    by_id: MutMap<Layout<'a>, u32>,
+    next_id: u32,
+}
+
+#[derive(Default)]
+pub struct LayoutIds<'a> {
+    by_symbol: MutMap<Symbol, IdsByLayout<'a>>,
+}
+
+impl<'a> LayoutIds<'a> {
+    /// Returns a LayoutId which is unique for the given symbol and layout.
+    /// If given the same symbol and same layout, returns the same LayoutId.
+    pub fn get(&mut self, symbol: Symbol, layout: &Layout<'a>) -> LayoutId {
+        // Note: this function does some weird stuff to satisfy the borrow checker.
+        // There's probably a nicer way to write it that still works.
+        let ids = self.by_symbol.entry(symbol).or_insert_with(|| IdsByLayout {
+            by_id: HashMap::with_capacity_and_hasher(1, default_hasher()),
+            next_id: 1,
+        });
+
+        // Get the id associated with this layout, or default to next_id.
+        let answer = ids.by_id.get(layout).copied().unwrap_or(ids.next_id);
+
+        // If we had to default to next_id, it must not have been found;
+        // store the ID we're going to return and increment next_id.
+        if answer == ids.next_id {
+            ids.by_id.insert(layout.clone(), ids.next_id);
+
+            ids.next_id += 1;
+        }
+
+        LayoutId(answer)
+    }
+}

compiler/parse/src/ast.rs

@@ -392,6 +392,17 @@ pub enum CommentOrNewline<'a> {
     DocComment(&'a str),
 }
 
+impl<'a> CommentOrNewline<'a> {
+    pub fn is_comment(&self) -> bool {
+        use CommentOrNewline::*;
+        match self {
+            Newline => false,
+            LineComment(_) => true,
+            DocComment(_) => true,
+        }
+    }
+}
+
 #[derive(Clone, Debug, PartialEq)]
 pub enum Pattern<'a> {
     // Identifier