Merge pull request #678 from rtfeldman/record-bool-tests

More REPL Improvements

cli/src/repl/eval.rs

@@ -6,7 +6,7 @@ use roc_gen::{run_jit_function, run_jit_function_dynamic_type};
 use roc_module::ident::{Lowercase, TagName};
 use roc_module::operator::CalledVia;
 use roc_module::symbol::{Interns, ModuleId, Symbol};
-use roc_mono::layout::{Builtin, Layout};
+use roc_mono::layout::{union_sorted_tags_help, Builtin, Layout, UnionVariant};
 use roc_parse::ast::{AssignedField, Expr, StrLiteral};
 use roc_region::all::{Located, Region};
 use roc_types::subs::{Content, FlatType, Subs, Variable};
@@ -64,6 +64,10 @@ fn jit_to_ast_help<'a>(
                 env, num, content
             ))
         }
+        Layout::Builtin(Builtin::Int8) => {
+            // NOTE: this is does not handle 8-bit numbers yet
+            run_jit_function!(lib, main_fn_name, u8, |num| byte_to_ast(env, num, content))
+        }
         Layout::Builtin(Builtin::Int64) => {
             run_jit_function!(lib, main_fn_name, i64, |num| num_to_ast(
                 env,
@@ -89,19 +93,20 @@ fn jit_to_ast_help<'a>(
         Layout::Builtin(Builtin::List(_, elem_layout)) => run_jit_function!(
             lib,
             main_fn_name,
-            (*const libc::c_void, usize),
+            (*const u8, usize),
-            |(ptr, len): (*const libc::c_void, usize)| {
+            |(ptr, len): (*const u8, usize)| { list_to_ast(env, ptr, len, elem_layout, content) }
-                list_to_ast(env, ptr, len, elem_layout, content)
-            }
         ),
-        Layout::PhantomEmptyStruct => run_jit_function!(lib, main_fn_name, &'static str, |_| {
+        Layout::Builtin(other) => {
+            todo!("add support for rendering builtin {:?} to the REPL", other)
+        }
+        Layout::PhantomEmptyStruct => run_jit_function!(lib, main_fn_name, &u8, |_| {
             Expr::Record {
                 update: None,
                 fields: &[],
             }
         }),
         Layout::Struct(field_layouts) => {
-            let ptr_to_ast = |ptr: *const libc::c_void| match content {
+            let ptr_to_ast = |ptr: *const u8| match content {
                 Content::Structure(FlatType::Record(fields, _)) => {
                     struct_to_ast(env, ptr, field_layouts, fields)
                 }
@@ -113,13 +118,7 @@ fn jit_to_ast_help<'a>(
 
                     let (tag_name, payload_vars) = tags.iter().next().unwrap();
 
-                    // We expect anything with payload vars
+                    single_tag_union_to_ast(env, ptr, field_layouts, tag_name.clone(), payload_vars)
-                    // that is a single Tag TagUnion
-                    // has a Record content so the above case
-                    // should match instead
-                    debug_assert_eq!(payload_vars.len(), 0);
-
-                    single_tag_union_to_ast(env, field_layouts, tag_name.clone(), payload_vars)
                 }
                 other => {
                     unreachable!(
@@ -132,76 +131,93 @@ fn jit_to_ast_help<'a>(
             let fields = [Layout::Builtin(Builtin::Int64), layout.clone()];
             let layout = Layout::Struct(&fields);
 
-            match env.ptr_bytes {
+            let result_stack_size = layout.stack_size(env.ptr_bytes);
-                // 64-bit target (8-byte pointers, 16-byte structs)
+
-                8 => match layout.stack_size(env.ptr_bytes) {
-                    8 => {
-                        // just one eightbyte, returned as-is
-                        run_jit_function!(lib, main_fn_name, [u8; 8], |bytes: [u8; 8]| {
-                            ptr_to_ast((&bytes).as_ptr() as *const libc::c_void)
-                        })
-                    }
-                    16 => {
-                        // two eightbytes, returned as-is
-                        run_jit_function!(lib, main_fn_name, [u8; 16], |bytes: [u8; 16]| {
-                            ptr_to_ast((&bytes).as_ptr() as *const libc::c_void)
-                        })
-                    }
-                    larger_size => {
-                        // anything more than 2 eightbytes
-                        // the return "value" is a pointer to the result
             run_jit_function_dynamic_type!(
                 lib,
                 main_fn_name,
-                            larger_size as usize,
+                result_stack_size as usize,
-                            |bytes: *const u8| { ptr_to_ast(bytes as *const libc::c_void) }
+                |bytes: *const u8| { ptr_to_ast(bytes as *const u8) }
             )
         }
+        Layout::Union(union_layouts) => match content {
+            Content::Structure(FlatType::TagUnion(tags, _)) => {
+                debug_assert_eq!(union_layouts.len(), tags.len());
+
+                let tags_vec: std::vec::Vec<(TagName, std::vec::Vec<Variable>)> =
+                    tags.iter().map(|(a, b)| (a.clone(), b.clone())).collect();
+
+                let union_variant = union_sorted_tags_help(env.arena, tags_vec, None, env.subs);
+
+                let size = layout.stack_size(env.ptr_bytes);
+                match union_variant {
+                    UnionVariant::Wrapped(tags_and_layouts) => {
+                        run_jit_function_dynamic_type!(
+                            lib,
+                            main_fn_name,
+                            size as usize,
+                            |ptr: *const u8| {
+                                // Because this is a `Wrapped`, the first 8 bytes encode the tag ID
+                                let tag_id = *(ptr as *const i64);
+
+                                // use the tag ID as an index, to get its name and layout of any arguments
+                                let (tag_name, arg_layouts) = &tags_and_layouts[tag_id as usize];
+
+                                let tag_expr = tag_name_to_expr(env, tag_name);
+                                let loc_tag_expr = &*env.arena.alloc(Located::at_zero(tag_expr));
+
+                                let variables = &tags[tag_name];
+
+                                // because the arg_layouts include the tag ID, it is one longer
+                                debug_assert_eq!(arg_layouts.len() - 1, variables.len());
+
+                                // skip forward to the start of the first element, ignoring the tag id
+                                let ptr = ptr.offset(8);
+
+                                let it = variables.iter().copied().zip(&arg_layouts[1..]);
+                                let output = sequence_of_expr(env, ptr, it);
+                                let output = output.into_bump_slice();
+
+                                Expr::Apply(loc_tag_expr, output, CalledVia::Space)
+                            }
+                        )
+                    }
+                    _ => unreachable!("any other variant would have a different layout"),
+                }
+            }
+            Content::Structure(FlatType::RecursiveTagUnion(_, _, _)) => {
+                todo!("print recursive tag unions in the REPL")
+            }
+            other => unreachable!("Weird content for Union layout: {:?}", other),
         },
-                // 32-bit target (4-byte pointers, 8-byte structs)
+        Layout::RecursiveUnion(_) | Layout::RecursivePointer => {
-                4 => {
+            todo!("add support for rendering recursive tag unions in the REPL")
-                    // TODO what are valid return sizes here?
-                    // this is just extrapolated from the 64-bit case above
-                    // and not (yet) actually tested on a 32-bit system
-                    match layout.stack_size(env.ptr_bytes) {
-                        4 => {
-                            // just one fourbyte, returned as-is
-                            run_jit_function!(lib, main_fn_name, [u8; 4], |bytes: [u8; 4]| {
-                                ptr_to_ast((&bytes).as_ptr() as *const libc::c_void)
-                            })
         }
-                        8 => {
+
-                            // just one fourbyte, returned as-is
+        Layout::FunctionPointer(_, _) | Layout::Closure(_, _, _) => {
-                            run_jit_function!(lib, main_fn_name, [u8; 8], |bytes: [u8; 8]| {
+            todo!("add support for rendering functions in the REPL")
-                                ptr_to_ast((&bytes).as_ptr() as *const libc::c_void)
-                            })
         }
-                        larger_size => {
+        Layout::Pointer(_) => todo!("add support for rendering pointers in the REPL"),
-                            // anything more than 2 fourbytes
-                            // the return "value" is a pointer to the result
-                            run_jit_function_dynamic_type!(
-                                lib,
-                                main_fn_name,
-                                larger_size as usize,
-                                |bytes: *const u8| { ptr_to_ast(bytes as *const libc::c_void) }
-                            )
-                        }
-                    }
-                }
-                other => {
-                    panic!("Unsupported target: Roc cannot currently compile to systems where pointers are {} bytes in length.", other);
-                }
-            }
-        }
-        other => {
-            todo!("TODO add support for rendering {:?} in the REPL", other);
     }
+}
+
+fn tag_name_to_expr<'a>(env: &Env<'a, '_>, tag_name: &TagName) -> Expr<'a> {
+    match tag_name {
+        TagName::Global(_) => Expr::GlobalTag(
+            env.arena
+                .alloc_str(&tag_name.as_string(env.interns, env.home)),
+        ),
+        TagName::Private(_) => Expr::PrivateTag(
+            env.arena
+                .alloc_str(&tag_name.as_string(env.interns, env.home)),
+        ),
+        TagName::Closure(_) => unreachable!("User cannot type this"),
     }
 }
 
 fn ptr_to_ast<'a>(
     env: &Env<'a, '_>,
-    ptr: *const libc::c_void,
+    ptr: *const u8,
     layout: &Layout<'a>,
     content: &Content,
 ) -> Expr<'a> {
@@ -227,7 +243,7 @@ fn ptr_to_ast<'a>(
         Layout::Builtin(Builtin::List(_, elem_layout)) => {
             // Turn the (ptr, len) wrapper struct into actual ptr and len values.
             let len = unsafe { *(ptr.offset(env.ptr_bytes as isize) as *const usize) };
-            let ptr = unsafe { *(ptr as *const *const libc::c_void) };
+            let ptr = unsafe { *(ptr as *const *const u8) };
 
             list_to_ast(env, ptr, len, elem_layout, content)
         }
@@ -241,6 +257,12 @@ fn ptr_to_ast<'a>(
             Content::Structure(FlatType::Record(fields, _)) => {
                 struct_to_ast(env, ptr, field_layouts, fields)
             }
+            Content::Structure(FlatType::TagUnion(tags, _)) => {
+                debug_assert_eq!(tags.len(), 1);
+
+                let (tag_name, payload_vars) = tags.iter().next().unwrap();
+                single_tag_union_to_ast(env, ptr, field_layouts, tag_name.clone(), payload_vars)
+            }
             other => {
                 unreachable!(
                     "Something had a Struct layout, but instead of a Record type, it had: {:?}",
@@ -259,7 +281,7 @@ fn ptr_to_ast<'a>(
 
 fn list_to_ast<'a>(
     env: &Env<'a, '_>,
-    ptr: *const libc::c_void,
+    ptr: *const u8,
     len: usize,
     elem_layout: &Layout<'a>,
     content: &Content,
@@ -282,11 +304,11 @@ fn list_to_ast<'a>(
 
     let arena = env.arena;
     let mut output = Vec::with_capacity_in(len, &arena);
-    let elem_size = elem_layout.stack_size(env.ptr_bytes);
+    let elem_size = elem_layout.stack_size(env.ptr_bytes) as usize;
 
-    for index in 0..(len as isize) {
+    for index in 0..len {
-        let offset_bytes: isize = index * elem_size as isize;
+        let offset_bytes = index * elem_size;
-        let elem_ptr = unsafe { ptr.offset(offset_bytes) };
+        let elem_ptr = unsafe { ptr.add(offset_bytes) };
         let loc_expr = &*arena.alloc(Located {
             value: ptr_to_ast(env, elem_ptr, elem_layout, &elem_content),
             region: Region::zero(),
@@ -302,7 +324,8 @@ fn list_to_ast<'a>(
 
 fn single_tag_union_to_ast<'a>(
     env: &Env<'a, '_>,
-    field_layouts: &[Layout<'a>],
+    ptr: *const u8,
+    field_layouts: &'a [Layout<'a>],
     tag_name: TagName,
     payload_vars: &[Variable],
 ) -> Expr<'a> {
@@ -310,28 +333,50 @@ fn single_tag_union_to_ast<'a>(
 
     let arena = env.arena;
 
-    let tag_expr = match tag_name {
+    let tag_expr = tag_name_to_expr(env, &tag_name);
-        TagName::Global(_) => {
-            Expr::GlobalTag(arena.alloc_str(&tag_name.as_string(env.interns, env.home)))
-        }
-        TagName::Private(_) => {
-            Expr::PrivateTag(arena.alloc_str(&tag_name.as_string(env.interns, env.home)))
-        }
-        TagName::Closure(_) => unreachable!("User cannot type this"),
-    };
 
-    let loc_tag_expr = &*arena.alloc(Located {
+    let loc_tag_expr = &*arena.alloc(Located::at_zero(tag_expr));
-        value: tag_expr,
-        region: Region::zero(),
-    });
 
-    Expr::Apply(loc_tag_expr, &[], CalledVia::Space)
+    let it = payload_vars.iter().copied().zip(field_layouts);
+    let output = sequence_of_expr(env, ptr as *const u8, it).into_bump_slice();
+
+    Expr::Apply(loc_tag_expr, output, CalledVia::Space)
+}
+
+fn sequence_of_expr<'a, I>(
+    env: &Env<'a, '_>,
+    ptr: *const u8,
+    sequence: I,
+) -> Vec<'a, &'a Located<Expr<'a>>>
+where
+    I: Iterator<Item = (Variable, &'a Layout<'a>)>,
+    I: ExactSizeIterator<Item = (Variable, &'a Layout<'a>)>,
+{
+    let arena = env.arena;
+    let subs = env.subs;
+    let mut output = Vec::with_capacity_in(sequence.len(), &arena);
+
+    // We'll advance this as we iterate through the fields
+    let mut field_ptr = ptr as *const u8;
+
+    for (var, layout) in sequence {
+        let content = subs.get_without_compacting(var).content;
+        let expr = ptr_to_ast(env, field_ptr, layout, &content);
+        let loc_expr = Located::at_zero(expr);
+
+        output.push(&*arena.alloc(loc_expr));
+
+        // Advance the field pointer to the next field.
+        field_ptr = unsafe { field_ptr.offset(layout.stack_size(env.ptr_bytes) as isize) };
+    }
+
+    output
 }
 
 fn struct_to_ast<'a>(
     env: &Env<'a, '_>,
-    ptr: *const libc::c_void,
+    ptr: *const u8,
-    field_layouts: &[Layout<'a>],
+    field_layouts: &'a [Layout<'a>],
     fields: &MutMap<Lowercase, RecordField<Variable>>,
 ) -> Expr<'a> {
     let arena = env.arena;
@@ -339,7 +384,7 @@ fn struct_to_ast<'a>(
     let mut output = Vec::with_capacity_in(field_layouts.len(), &arena);
 
     // The fields, sorted alphabetically
-    let sorted_fields = {
+    let mut sorted_fields = {
         let mut vec = fields
             .iter()
             .collect::<std::vec::Vec<(&Lowercase, &RecordField<Variable>)>>();
@@ -349,6 +394,33 @@ fn struct_to_ast<'a>(
         vec
     };
 
+    if sorted_fields.len() == 1 {
+        // this is a 1-field wrapper record around another record or 1-tag tag union
+        let (label, field) = sorted_fields.pop().unwrap();
+
+        let inner_content = env.subs.get_without_compacting(field.into_inner()).content;
+
+        let loc_expr = &*arena.alloc(Located {
+            value: ptr_to_ast(env, ptr, &Layout::Struct(field_layouts), &inner_content),
+            region: Region::zero(),
+        });
+
+        let field_name = Located {
+            value: &*arena.alloc_str(label.as_str()),
+            region: Region::zero(),
+        };
+        let loc_field = Located {
+            value: AssignedField::RequiredValue(field_name, &[], loc_expr),
+            region: Region::zero(),
+        };
+
+        let output = env.arena.alloc([loc_field]);
+
+        Expr::Record {
+            update: None,
+            fields: output,
+        }
+    } else {
         debug_assert_eq!(sorted_fields.len(), field_layouts.len());
 
         // We'll advance this as we iterate through the fields
@@ -373,7 +445,8 @@ fn struct_to_ast<'a>(
             output.push(loc_field);
 
             // Advance the field pointer to the next field.
-        field_ptr = unsafe { field_ptr.offset(field_layout.stack_size(env.ptr_bytes) as isize) };
+            field_ptr =
+                unsafe { field_ptr.offset(field_layout.stack_size(env.ptr_bytes) as isize) };
         }
 
         let output = output.into_bump_slice();
@@ -382,6 +455,7 @@ fn struct_to_ast<'a>(
             update: None,
             fields: output,
         }
+    }
 }
 
 fn bool_to_ast<'a>(env: &Env<'a, '_>, value: bool, content: &Content) -> Expr<'a> {
@@ -468,20 +542,17 @@ fn bool_to_ast<'a>(env: &Env<'a, '_>, value: bool, content: &Content) -> Expr<'a
                     debug_assert!(payload_vars_1.is_empty());
                     debug_assert!(payload_vars_2.is_empty());
 
-                    let tag_name_as_str_1 = &tag_name_1.as_string(env.interns, env.home);
-                    let tag_name_as_str_2 = &tag_name_2.as_string(env.interns, env.home);
-
                     let tag_name = if value {
-                        tag_name_as_str_1.max(tag_name_as_str_2)
+                        max_by_key(tag_name_1, tag_name_2, |n| {
+                            n.as_string(env.interns, env.home)
+                        })
                     } else {
-                        tag_name_as_str_1.min(tag_name_as_str_2)
+                        min_by_key(tag_name_1, tag_name_2, |n| {
+                            n.as_string(env.interns, env.home)
+                        })
                     };
 
-                    if tag_name.starts_with('@') {
+                    tag_name_to_expr(env, tag_name)
-                        Expr::PrivateTag(arena.alloc_str(tag_name))
-                    } else {
-                        Expr::GlobalTag(arena.alloc_str(tag_name))
-                    }
                 }
                 other => {
                     unreachable!("Unexpected FlatType {:?} in bool_to_ast", other);
@@ -499,6 +570,117 @@ fn bool_to_ast<'a>(env: &Env<'a, '_>, value: bool, content: &Content) -> Expr<'a
     }
 }
 
+fn byte_to_ast<'a>(env: &Env<'a, '_>, value: u8, content: &Content) -> Expr<'a> {
+    use Content::*;
+
+    let arena = env.arena;
+
+    match content {
+        Structure(flat_type) => {
+            match flat_type {
+                FlatType::Record(fields, _) => {
+                    debug_assert_eq!(fields.len(), 1);
+
+                    let (label, field) = fields.iter().next().unwrap();
+                    let loc_label = Located {
+                        value: &*arena.alloc_str(label.as_str()),
+                        region: Region::zero(),
+                    };
+
+                    let assigned_field = {
+                        // We may be multiple levels deep in nested tag unions
+                        // and/or records (e.g. { a: { b: { c: True }  } }),
+                        // so we need to do this recursively on the field type.
+                        let field_var = *field.as_inner();
+                        let field_content = env.subs.get_without_compacting(field_var).content;
+                        let loc_expr = Located {
+                            value: byte_to_ast(env, value, &field_content),
+                            region: Region::zero(),
+                        };
+
+                        AssignedField::RequiredValue(loc_label, &[], arena.alloc(loc_expr))
+                    };
+
+                    let loc_assigned_field = Located {
+                        value: assigned_field,
+                        region: Region::zero(),
+                    };
+
+                    Expr::Record {
+                        update: None,
+                        fields: arena.alloc([loc_assigned_field]),
+                    }
+                }
+                FlatType::TagUnion(tags, _) if tags.len() == 1 => {
+                    let (tag_name, payload_vars) = tags.iter().next().unwrap();
+
+                    let loc_tag_expr = {
+                        let tag_name = &tag_name.as_string(env.interns, env.home);
+                        let tag_expr = if tag_name.starts_with('@') {
+                            Expr::PrivateTag(arena.alloc_str(tag_name))
+                        } else {
+                            Expr::GlobalTag(arena.alloc_str(tag_name))
+                        };
+
+                        &*arena.alloc(Located {
+                            value: tag_expr,
+                            region: Region::zero(),
+                        })
+                    };
+
+                    let payload = {
+                        // Since this has the layout of a number, there should be
+                        // exactly one payload in this tag.
+                        debug_assert_eq!(payload_vars.len(), 1);
+
+                        let var = *payload_vars.iter().next().unwrap();
+                        let content = env.subs.get_without_compacting(var).content;
+
+                        let loc_payload = &*arena.alloc(Located {
+                            value: byte_to_ast(env, value, &content),
+                            region: Region::zero(),
+                        });
+
+                        arena.alloc([loc_payload])
+                    };
+
+                    Expr::Apply(loc_tag_expr, payload, CalledVia::Space)
+                }
+                FlatType::TagUnion(tags, _) => {
+                    // anything with fewer tags is not a byte
+                    debug_assert!(tags.len() > 2);
+
+                    let tags_vec: std::vec::Vec<(TagName, std::vec::Vec<Variable>)> =
+                        tags.iter().map(|(a, b)| (a.clone(), b.clone())).collect();
+
+                    let union_variant = union_sorted_tags_help(env.arena, tags_vec, None, env.subs);
+
+                    match union_variant {
+                        UnionVariant::ByteUnion(tagnames) => {
+                            let tag_name = &tagnames[value as usize];
+                            let tag_expr = tag_name_to_expr(env, tag_name);
+                            let loc_tag_expr = Located::at_zero(tag_expr);
+                            Expr::Apply(env.arena.alloc(loc_tag_expr), &[], CalledVia::Space)
+                        }
+                        _ => unreachable!("invalid union variant for a Byte!"),
+                    }
+                }
+                other => {
+                    unreachable!("Unexpected FlatType {:?} in bool_to_ast", other);
+                }
+            }
+        }
+        Alias(_, _, var) => {
+            let content = env.subs.get_without_compacting(*var).content;
+
+            byte_to_ast(env, value, &content)
+        }
+        other => {
+            unreachable!("Unexpected FlatType {:?} in bool_to_ast", other);
+        }
+    }
+}
+
 fn num_to_ast<'a>(env: &Env<'a, '_>, num_expr: Expr<'a>, content: &Content) -> Expr<'a> {
     use Content::*;
 
@@ -648,3 +830,30 @@ fn str_slice_to_ast<'a>(_arena: &'a Bump, string: &'a str) -> Expr<'a> {
         Expr::Str(StrLiteral::PlainLine(string))
     }
 }
+
+// TODO this is currently nighly-only: use the implementation in std once it's stabilized
+pub fn max_by<T, F: FnOnce(&T, &T) -> std::cmp::Ordering>(v1: T, v2: T, compare: F) -> T {
+    use std::cmp::Ordering;
+
+    match compare(&v1, &v2) {
+        Ordering::Less | Ordering::Equal => v2,
+        Ordering::Greater => v1,
+    }
+}
+
+pub fn min_by<T, F: FnOnce(&T, &T) -> std::cmp::Ordering>(v1: T, v2: T, compare: F) -> T {
+    use std::cmp::Ordering;
+
+    match compare(&v1, &v2) {
+        Ordering::Less | Ordering::Equal => v1,
+        Ordering::Greater => v2,
+    }
+}
+
+pub fn max_by_key<T, F: FnMut(&T) -> K, K: Ord>(v1: T, v2: T, mut f: F) -> T {
+    max_by(v1, v2, |v1, v2| f(v1).cmp(&f(v2)))
+}
+
+pub fn min_by_key<T, F: FnMut(&T) -> K, K: Ord>(v1: T, v2: T, mut f: F) -> T {
+    min_by(v1, v2, |v1, v2| f(v1).cmp(&f(v2)))
+}

cli/tests/repl_eval.rs

@@ -90,12 +90,15 @@ mod repl_eval {
     #[test]
     fn bool_in_record() {
         expect_success("{ x: 1 == 1 }", "{ x: True } : { x : Bool }");
+        expect_success(
+            "{ z: { y: { x: 1 == 1 } } }",
+            "{ z: { y: { x: True } } } : { z : { y : { x : Bool } } }",
+        );
         expect_success("{ x: 1 != 1 }", "{ x: False } : { x : Bool }");
-        // TODO: see ptr_to_ast
+        expect_success(
-        // expect_success(
+            "{ x: 1 == 1, y: 1 != 1 }",
-        //     "{ x: 1 == 1, y: 1 != 1 }",
+            "{ x: True, y: False } : { x : Bool, y : Bool }",
-        //     "{ x: True, y: False } : { x : Bool, y : Bool }",
+        );
-        // );
     }
 
     #[test]
@@ -116,14 +119,46 @@ mod repl_eval {
         expect_success("False", "False : [ False ]*");
     }
 
+    #[test]
+    fn byte_tag_union() {
+        expect_success(
+            "if 1 == 1 then Red else if 1 == 1 then Green else Blue",
+            "Red : [ Blue, Green, Red ]*",
+        );
+
+        expect_success(
+            "{ y: { x: if 1 == 1 then Red else if 1 == 1 then Green else Blue } }",
+            "{ y: { x: Red } } : { y : { x : [ Blue, Green, Red ]* } }",
+        );
+    }
+
+    #[test]
+    fn tag_in_record() {
+        expect_success(
+            "{ x: Foo 1 2 3, y : 4 }",
+            "{ x: Foo 1 2 3, y: 4 } : { x : [ Foo (Num *) (Num *) (Num *) ]*, y : Num * }",
+        );
+        expect_success(
+            "{ x: Foo 1 2 3 }",
+            "{ x: Foo 1 2 3 } : { x : [ Foo (Num *) (Num *) (Num *) ]* }",
+        );
+        expect_success("{ x: Unit }", "{ x: Unit } : { x : [ Unit ]* }");
+    }
+
+    #[test]
+    fn single_element_tag_union() {
+        expect_success("True 1", "True 1 : [ True (Num *) ]*");
+        expect_success("Foo 1 3.14", "Foo 1 3.14 : [ Foo (Num *) Float ]*");
+    }
+
     #[test]
     fn tag_with_arguments() {
         expect_success("True 1", "True 1 : [ True (Num *) ]*");
-        // TODO handle more situations
+
-        // expect_success(
+        expect_success(
-        //     "if 1 == 1 then True 1 else False 3.14",
+            "if 1 == 1 then True 3 else False 3.14",
-        //     "True 1 : [ True (Num *), False Float ]*",
+            "True 3 : [ False Float, True (Num *) ]*",
-        // )
+        )
     }
 
     #[test]
@@ -273,32 +308,29 @@ mod repl_eval {
         );
     }
 
-    // TODO uncomment this once https://github.com/rtfeldman/roc/issues/295 is done
+    #[test]
-    // #[test]
+    fn basic_2_field_f64_record() {
-    // fn basic_2_field_f64_record() {
+        expect_success(
-    //     expect_success(
+            "{ foo: 4.1, bar: 2.3 }",
-    //         "{ foo: 4.1, bar: 2.3 }",
+            "{ bar: 2.3, foo: 4.1 } : { bar : Float, foo : Float }",
-    //         "{ bar: 2.3, foo: 4.1 } : { bar : Float, foo : Float }",
+        );
-    //     );
+    }
-    // }
 
-    // #[test]
+    #[test]
-    // fn basic_2_field_mixed_record() {
+    fn basic_2_field_mixed_record() {
-    //     expect_success(
+        expect_success(
-    //         "{ foo: 4.1, bar: 2 }",
+            "{ foo: 4.1, bar: 2 }",
-    //         "{ bar: 2, foo: 4.1 } : { bar : Num *, foo : Float }",
+            "{ bar: 2, foo: 4.1 } : { bar : Num *, foo : Float }",
-    //     );
+        );
-    // }
+    }
 
-    // TODO uncomment this once https://github.com/rtfeldman/roc/issues/295 is done
+    #[test]
-    //
+    fn basic_3_field_record() {
-    // #[test]
+        expect_success(
-    // fn basic_3_field_record() {
+            "{ foo: 4.1, bar: 2, baz: 0x5 }",
-    //     expect_success(
+            "{ bar: 2, baz: 5, foo: 4.1 } : { bar : Num *, baz : Int, foo : Float }",
-    //         "{ foo: 4.1, bar: 2, baz: 0x5 }",
+        );
-    //         "{ foo: 4.1, bar: 2, baz: 0x5 } : { foo : Float, bar : Num *, baz : Int }",
+    }
-    //     );
-    // }
 
     #[test]
     fn list_of_1_field_records() {

compiler/gen/tests/gen_records.rs

@@ -820,4 +820,28 @@ mod gen_records {
             i64
         );
     }
+
+    #[test]
+    fn booleans_in_record() {
+        assert_evals_to!(
+            indoc!("{ x: 1 == 1, y: 1 == 1 }"),
+            (true, true),
+            (bool, bool)
+        );
+        assert_evals_to!(
+            indoc!("{ x: 1 != 1, y: 1 == 1 }"),
+            (false, true),
+            (bool, bool)
+        );
+        assert_evals_to!(
+            indoc!("{ x: 1 == 1, y: 1 != 1 }"),
+            (true, false),
+            (bool, bool)
+        );
+        assert_evals_to!(
+            indoc!("{ x: 1 != 1, y: 1 != 1 }"),
+            (false, false),
+            (bool, bool)
+        );
+    }
 }

compiler/mono/src/layout.rs

@@ -936,7 +936,7 @@ fn get_recursion_var(subs: &Subs, var: Variable) -> Option<Variable> {
     }
 }
 
-fn union_sorted_tags_help<'a>(
+pub fn union_sorted_tags_help<'a>(
     arena: &'a Bump,
     mut tags_vec: std::vec::Vec<(TagName, std::vec::Vec<Variable>)>,
     opt_rec_var: Option<Variable>,

shell.nix

@@ -16,8 +16,7 @@ with {
 with (pkgs);
 
 let
-  darwin-frameworks =
+  darwin-frameworks = if isMacOS then
-    if isMacOS then
     with pkgs.darwin.apple_sdk.frameworks; [
       AppKit
       CoreFoundation
@@ -29,12 +28,24 @@ let
     ]
   else
     [ ];
+
+  linux-only = if !isMacOS then [
+    vulkan-headers
+    vulkan-loader
+    vulkan-tools
+    vulkan-validation-layers
+    xorg.libX11
+    xorg.libXcursor
+    xorg.libXrandr
+    xorg.libXi
+  ] else
+    [ ];
+
   llvmPkg = pkgs.llvm_10;
   lldPkg = pkgs.lld_10; # this should match llvm's version
   clangPkg = pkgs.clang_10; # this should match llvm's version
   zig = import ./nix/zig.nix { inherit pkgs isMacOS; };
-  inputs =
+  inputs = [
-    [
     # build libraries
     rustc
     cargo
@@ -51,12 +62,7 @@ let
     # llb deps
     libffi
     libxml2
-      xorg.libX11
     zlib
-      vulkan-headers
-      vulkan-loader
-      vulkan-tools
-      vulkan-validation-layers
     # faster builds - see https://github.com/rtfeldman/roc/blob/trunk/BUILDING_FROM_SOURCE.md#use-lld-for-the-linker
     lldPkg
     # dev tools
@@ -64,24 +70,13 @@ let
     # (import ./nix/zls.nix { inherit pkgs zig; })
     ccls
   ];
+
 in mkShell {
-  buildInputs = inputs ++ darwin-frameworks;
+  buildInputs = inputs ++ darwin-frameworks ++ linux-only;
   LLVM_SYS_100_PREFIX = "${llvmPkg}";
 
-  APPEND_LIBRARY_PATH = stdenv.lib.makeLibraryPath [
+  APPEND_LIBRARY_PATH = stdenv.lib.makeLibraryPath
-      pkgconfig
+    ([ pkgconfig libcxx libcxxabi libunwind ] ++ linux-only);
-      vulkan-headers
-      vulkan-loader
-      vulkan-tools
-      vulkan-validation-layers
-      xorg.libX11
-      xorg.libXcursor
-      xorg.libXrandr
-      xorg.libXi
-      libcxx
-      libcxxabi
-      libunwind
-    ];
 
   # Aliases don't work cross shell, so we do this
   shellHook = ''