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Merge pull request #6649 from roc-lang/suffixed-when

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Add support for suffixed `when` expressions
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Richard Feldman 2024-04-18 22:15:28 -04:00 • committed by GitHub
commit ca8682e93c
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2 changed files with 127 additions and 4 deletions
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58
crates/compiler/can/src/suffixed.rs
View file

@ -6,7 +6,7 @@ use roc_error_macros::internal_error;
use roc_module::called_via::CalledVia;
use roc_module::ident::ModuleName;
use roc_parse::ast::Expr::{self, *};
use roc_parse::ast::{is_loc_expr_suffixed, wrap_in_task_ok, Pattern, ValueDef};
use roc_parse::ast::{is_loc_expr_suffixed, wrap_in_task_ok, Pattern, ValueDef, WhenBranch};
use roc_region::all::{Loc, Region};
use std::cell::Cell;
@ -564,11 +564,61 @@ pub fn unwrap_suffixed_expression_if_then_else_help<'a>(
}
pub fn unwrap_suffixed_expression_when_help<'a>(
_arena: &'a Bump,
arena: &'a Bump,
loc_expr: &'a Loc<Expr<'a>>,
_maybe_def_pat: Option<&'a Loc<Pattern<'a>>>,
maybe_def_pat: Option<&'a Loc<Pattern<'a>>>,
) -> Result<&'a Loc<Expr<'a>>, EUnwrapped<'a>> {
Ok(loc_expr)
match loc_expr.value {
Expr::When(condition, branches) => {
// first unwrap any when branches values
// e.g.
// when foo is
// [] -> line! "bar"
// _ -> line! "baz"
for (branch_index, WhenBranch{value: branch_loc_expr,patterns, guard}) in branches.iter().enumerate() {
// if the branch isn't suffixed we can leave it alone
if is_loc_expr_suffixed(branch_loc_expr) {
let unwrapped_branch_value = match unwrap_suffixed_expression(arena, branch_loc_expr, None) {
Ok(unwrapped_branch_value) => unwrapped_branch_value,
Err(EUnwrapped::UnwrappedSubExpr { sub_arg, sub_pat, sub_new }) => apply_task_await(arena, branch_loc_expr.region, sub_arg, sub_pat, sub_new),
Err(..) => return Err(EUnwrapped::Malformed),
};
let new_branch = WhenBranch{value: *unwrapped_branch_value, patterns, guard: *guard};
let mut new_branches = Vec::new_in(arena);
let (before, rest) = branches.split_at(branch_index);
let after = &rest[1..];
new_branches.extend_from_slice(before);
new_branches.push(arena.alloc(new_branch));
new_branches.extend_from_slice(after);
let new_when = arena.alloc(Loc::at(loc_expr.region, Expr::When(condition, arena.alloc_slice_copy(new_branches.as_slice()))));
return unwrap_suffixed_expression(arena, new_when, maybe_def_pat);
}
}
// then unwrap the when condition
match unwrap_suffixed_expression(arena, condition, None) {
Ok(unwrapped_condition) => {
let new_when = arena.alloc(Loc::at(loc_expr.region, Expr::When(unwrapped_condition, branches)));
Ok(new_when)
}
Err(EUnwrapped::UnwrappedSubExpr { sub_arg, sub_pat, sub_new }) => {
let new_when = arena.alloc(Loc::at(loc_expr.region, Expr::When(sub_new, branches)));
let applied_task_await = apply_task_await(arena,loc_expr.region,sub_arg,sub_pat,new_when);
Ok(applied_task_await)
}
Err(EUnwrapped::UnwrappedDefExpr(..))
| Err(EUnwrapped::Malformed) => Err(EUnwrapped::Malformed)
}
}
_ => internal_error!("unreachable, expected a When node to be passed into unwrap_suffixed_expression_defs_help"),
}
}
pub fn unwrap_suffixed_expression_defs_help<'a>(

73
crates/compiler/can/tests/test_suffixed.rs
View file

@ -665,4 +665,77 @@ mod suffixed_tests {
r#"Defs { tags: [Index(2147483648)], regions: [@0-103], space_before: [Slice(start = 0, length = 0)], space_after: [Slice(start = 0, length = 0)], spaces: [], type_defs: [], value_defs: [Body(@0-4 Identifier { ident: "copy", suffixed: 0 }, @7-103 Closure([@8-9 Identifier { ident: "a", suffixed: 0 }, @10-11 Identifier { ident: "b", suffixed: 0 }], @36-42 Apply(@36-42 Var { module_name: "Task", ident: "await", suffixed: 0 }, [@36-42 Apply(@36-42 Var { module_name: "", ident: "line", suffixed: 0 }, [@37-42 Str(PlainLine("FOO"))], Space), @36-42 Closure([@36-42 RecordDestructure([])], @60-103 Apply(@60-103 Var { module_name: "", ident: "mapErr", suffixed: 0 }, [@60-72 Apply(@60-67 Var { module_name: "CMD", ident: "new", suffixed: 0 }, [@68-72 Str(PlainLine("cp"))], Space), @100-103 Tag("ERR")], BinOp(Pizza)))], BangSuffix)))] }"#,
);
}
/**
* Unwrap a when expression
```roc
list =
when getList! is
[] -> "empty"
_ -> "non-empty"
list =
Task.await getList \#!a0 ->
when #!a0 is
[] -> "empty"
_ -> "non-empty"
```
*/
#[test]
fn when_simple() {
run_test(
r#"
list =
when getList! is
[] -> "empty"
_ -> "non-empty"
"#,
r##"Defs { tags: [Index(2147483648)], regions: [@0-111], space_before: [Slice(start = 0, length = 0)], space_after: [Slice(start = 0, length = 0)], spaces: [], type_defs: [], value_defs: [Body(@0-4 Identifier { ident: "list", suffixed: 0 }, @24-111 Apply(@24-111 Var { module_name: "Task", ident: "await", suffixed: 0 }, [@29-37 Var { module_name: "", ident: "getList", suffixed: 0 }, @24-111 Closure([@29-37 Identifier { ident: "#!a0", suffixed: 0 }], @24-111 When(@29-37 Var { module_name: "", ident: "#!a0", suffixed: 0 }, [WhenBranch { patterns: [@61-63 List([])], value: @67-74 Str(PlainLine("empty")), guard: None }, WhenBranch { patterns: [@95-96 Underscore("")], value: @100-111 Str(PlainLine("non-empty")), guard: None }]))], BangSuffix))] }"##,
);
}
/**
* Unwrap a when expression
```roc
list =
when getList! is
[] ->
line! "foo"
line! "bar"
_ ->
ok {}
list =
Task.await getList \#!a0 ->
when getList is
[] ->
line! "foo"
line! "bar"
_ ->
ok {}
list =
Task.await getList \#!a0 ->
when getList is
[] ->
Task.await line "foo" \{} -> line! "bar"
_ ->
ok {}
```
*/
#[test]
fn when_branches() {
run_test(
r#"
list =
when getList! is
[] ->
line! "foo"
line! "bar"
_ ->
ok {}
"#,
r##"Defs { tags: [Index(2147483648)], regions: [@0-195], space_before: [Slice(start = 0, length = 0)], space_after: [Slice(start = 0, length = 0)], spaces: [], type_defs: [], value_defs: [Body(@0-4 Identifier { ident: "list", suffixed: 0 }, @24-195 Apply(@24-195 Var { module_name: "Task", ident: "await", suffixed: 0 }, [@29-37 Var { module_name: "", ident: "getList", suffixed: 0 }, @24-195 Closure([@29-37 Identifier { ident: "#!a0", suffixed: 0 }], @24-195 When(@29-37 Var { module_name: "", ident: "#!a0", suffixed: 0 }, [WhenBranch { patterns: [@61-63 List([])], value: @97-103 Apply(@97-103 Var { module_name: "Task", ident: "await", suffixed: 0 }, [@97-103 Apply(@97-103 Var { module_name: "", ident: "line", suffixed: 0 }, [@98-103 Str(PlainLine("foo"))], Space), @97-103 Closure([@97-103 RecordDestructure([])], @128-139 Apply(@128-139 Var { module_name: "", ident: "line", suffixed: 0 }, [@134-139 Str(PlainLine("bar"))], Space))], BangSuffix), guard: None }, WhenBranch { patterns: [@160-161 Underscore("")], value: @190-195 Apply(@190-192 Var { module_name: "", ident: "ok", suffixed: 0 }, [@193-195 Record([])], Space), guard: None }]))], BangSuffix))] }"##,
);
}
}