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add support for if-then-else
This commit is contained in:
Luke Boswell
parent
2a222f3a51
commit
ee42dfc317
2 changed files with 313 additions and 117 deletions
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@ -6,7 +6,7 @@ use roc_error_macros::internal_error;
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use roc_module::called_via::CalledVia;
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use roc_module::ident::ModuleName;
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use roc_parse::ast::Expr::{self, *};
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use roc_parse::ast::{Pattern, ValueDef};
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use roc_parse::ast::{is_loc_expr_suffixed, Pattern, ValueDef};
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use roc_region::all::{Loc, Region};
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use std::cell::Cell;
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@ -354,138 +354,243 @@ pub fn unwrap_suffixed_expression_apply_help<'a>(
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}
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}
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/// Unwrap if-then-else statements
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pub fn unwrap_suffixed_expression_if_then_else_help<'a>(
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_arena: &'a Bump,
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arena: &'a Bump,
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loc_expr: &'a Loc<Expr<'a>>,
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_maybe_def_pat: Option<&'a Loc<Pattern<'a>>>,
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maybe_def_pat: Option<&'a Loc<Pattern<'a>>>,
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) -> Result<&'a Loc<Expr<'a>>, EUnwrapped<'a>> {
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Ok(loc_expr)
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match loc_expr.value {
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Expr::If(if_thens, final_else_branch) => {
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for (index, if_then) in if_thens.iter().enumerate() {
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let (current_if_then_statement, current_if_then_expression) = if_then;
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// TODO - the logic below is mostly correct, however it needs to be
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// translated to this new method and tests added, leaving this for a future PR
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// unwrap suffixed (innermost) expressions e.g. `if true then doThing! then ...`
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if is_loc_expr_suffixed(current_if_then_expression) {
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// split if_thens around the current index
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let (before, after) = roc_parse::ast::split_around(if_thens, index);
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// consider each if-statement, if it is suffixed we need to desugar e.g.
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// ```
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// if isFalse! then
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// "fail"
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// else
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// if isTrue! then
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// "success"
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// else
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// "fail"
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// ```
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// desugars to
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// ```
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// Task.await (isFalse) \isAnswer0 ->
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// if isAnswer0 then
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// "fail"
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// else
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// Task.await (isTrue) \isAnswer1 ->
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// if isAnswer1 then
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// "success"
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// else
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// "fail"
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// ```
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//
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// Note there are four possible combinations that must be considered
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// 1. NIL if_thens before the first suffixed, and NIL after e.g. `if y! then "y" else "n"`
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// 2. NIL if_thens before the first suffixed, and SOME after e.g. `if n! then "n" else if y! "y" else "n"`
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// 3. SOME if_thens before the first suffixed, and NIL after e.g. `if n then "n" else if y! then "y" else "n"`
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// 4. SOME if_thens before the first suffixed, and SOME after e.g. `if n then "n" else if y! then "y" else if n then "n"`
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// fn desugar_if_node_suffixed<'a>(arena: &'a Bump, loc_expr: &'a Loc<Expr<'a>>) -> &'a Loc<Expr<'a>> {
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// match loc_expr.value {
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// Expr::If(if_thens, final_else_branch) => {
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// // Search for the first suffixied expression e.g. `if isThing! then ...`
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// for (index, if_then) in if_thens.iter().enumerate() {
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// let (current_if_then_statement, current_if_then_expression) = if_then;
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match unwrap_suffixed_expression(arena, current_if_then_expression, None) {
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Ok(unwrapped_expression) => {
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let mut new_if_thens = Vec::new_in(arena);
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// if is_loc_expr_suffixed(current_if_then_statement) {
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// // split if_thens around the current index
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// let (before, after) = roc_parse::ast::split_around(if_thens, index);
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new_if_thens.extend(before);
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new_if_thens.push((*current_if_then_statement, *unwrapped_expression));
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new_if_thens.extend(after);
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// // increment our global counter for ident suffixes
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// // this should be the only place this counter is referenced
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// SUFFIXED_IF_COUNTER.fetch_add(1, Ordering::SeqCst);
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// let count = SUFFIXED_IF_COUNTER.load(Ordering::SeqCst);
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let new_if = arena.alloc(Loc::at(
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loc_expr.region,
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Expr::If(
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arena.alloc_slice_copy(new_if_thens.as_slice()),
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final_else_branch,
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),
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));
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// // create a unique identifier for our answer
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// let answer_ident = arena.alloc(format!("#if!{}", count));
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// let pattern = Loc::at(
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// current_if_then_statement.region,
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// Pattern::Identifier {
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// ident: answer_ident,
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// suffixed: 0,
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// },
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// );
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return unwrap_suffixed_expression(arena, new_if, maybe_def_pat);
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}
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Err(EUnwrapped::UnwrappedDefExpr(..)) => {
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internal_error!("unexpected, unwrapped if-then-else Def expr should have intermediate answer as `None` was passed as pattern");
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}
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Err(EUnwrapped::UnwrappedSubExpr {
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sub_arg,
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sub_pat,
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sub_new,
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}) => {
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let ok_wrapped_return = arena.alloc(Loc::at(
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loc_expr.region,
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Expr::Apply(
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arena.alloc(Loc::at(
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loc_expr.region,
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Expr::Var {
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module_name: ModuleName::TASK,
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ident: "ok",
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suffixed: 0,
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},
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)),
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arena.alloc([sub_new]),
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CalledVia::BangSuffix,
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),
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));
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// // if we have any after the current index, we will recurse on these as they may also be suffixed
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// let remaining_loc_expr = if after.is_empty() {
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// final_else_branch
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// } else {
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// let after_if = arena
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// .alloc(Loc::at(loc_expr.region, Expr::If(after, final_else_branch)));
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let unwrapped_expression = apply_task_await(
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arena,
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sub_arg.region,
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sub_arg,
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sub_pat,
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ok_wrapped_return,
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);
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// desugar_if_node_suffixed(arena, after_if)
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// };
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let mut new_if_thens = Vec::new_in(arena);
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// let closure_expr = Closure(
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// arena.alloc([pattern]),
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// arena.alloc(Loc::at(
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// current_if_then_statement.region,
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// If(
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// arena.alloc_slice_clone(&[(
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// Loc::at(
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// current_if_then_statement.region,
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// Var {
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// module_name: "",
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// ident: answer_ident,
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// suffixed: 0,
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// },
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// ),
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// *current_if_then_expression,
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// )]),
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// remaining_loc_expr,
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// ),
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// )),
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// );
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new_if_thens.extend(before);
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new_if_thens.push((*current_if_then_statement, *unwrapped_expression));
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new_if_thens.extend(after);
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// // Apply arguments to Task.await, first is the unwrapped Suffix expr second is the Closure
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// let mut task_await_apply_args: Vec<&'a Loc<Expr<'a>>> = Vec::new_in(arena);
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let new_if = arena.alloc(Loc::at(
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loc_expr.region,
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Expr::If(
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arena.alloc_slice_copy(new_if_thens.as_slice()),
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final_else_branch,
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),
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));
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// task_await_apply_args.push(current_if_then_statement);
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// task_await_apply_args.push(arena.alloc(Loc::at(loc_expr.region, closure_expr)));
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return unwrap_suffixed_expression(arena, new_if, maybe_def_pat);
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}
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Err(EUnwrapped::Malformed) => return Err(EUnwrapped::Malformed),
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}
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}
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// let applied_closure = arena.alloc(Loc::at(
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// loc_expr.region,
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// Apply(
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// arena.alloc(Loc {
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// region: loc_expr.region,
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// value: Var {
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// module_name: ModuleName::TASK,
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// ident: "await",
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// suffixed: 0,
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// },
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// }),
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// arena.alloc(task_await_apply_args),
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// CalledVia::BangSuffix,
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// ),
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// ));
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// unwrap suffixed statements e.g. `if isThing! then ...`
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// note we want to split and nest if-then's so we only run Task's
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// that are required
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if is_loc_expr_suffixed(current_if_then_statement) {
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// split if_thens around the current index
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let (before, after) = roc_parse::ast::split_around(if_thens, index);
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// if before.is_empty() {
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// return applied_closure;
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// } else {
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// return arena
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// .alloc(Loc::at(loc_expr.region, Expr::If(before, applied_closure)));
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// }
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// }
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// }
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match unwrap_suffixed_expression(arena, current_if_then_statement, None) {
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Ok(unwrapped_statement) => {
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let mut new_if_thens = Vec::new_in(arena);
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// // nothing was suffixed, so just return the original if-statement
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// loc_expr
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// }
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// _ => internal_error!("unreachable, expected an If expression to desugar"),
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// }
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// }
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new_if_thens.push((*unwrapped_statement, *current_if_then_expression));
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new_if_thens.extend(after);
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let new_if = arena.alloc(Loc::at(
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loc_expr.region,
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Expr::If(
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arena.alloc_slice_copy(new_if_thens.as_slice()),
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final_else_branch,
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),
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));
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return unwrap_suffixed_expression(arena, new_if, maybe_def_pat);
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}
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Err(EUnwrapped::UnwrappedDefExpr(..)) => {
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internal_error!("unexpected, unwrapped if-then-else Def expr should have intermediate answer as `None` was passed as pattern");
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}
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Err(EUnwrapped::UnwrappedSubExpr {
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sub_arg,
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sub_pat,
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sub_new,
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}) => {
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if before.is_empty() {
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let mut new_if_thens = Vec::new_in(arena);
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new_if_thens.extend(before);
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new_if_thens.push((*sub_new, *current_if_then_expression));
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new_if_thens.extend(after);
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let new_if = arena.alloc(Loc::at(
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loc_expr.region,
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Expr::If(
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arena.alloc_slice_copy(new_if_thens.as_slice()),
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final_else_branch,
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),
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));
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let unwrapped_if_then = apply_task_await(
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arena,
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sub_arg.region,
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sub_arg,
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sub_pat,
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new_if,
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);
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return unwrap_suffixed_expression(
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arena,
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unwrapped_if_then,
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maybe_def_pat,
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);
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} else {
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let mut after_if_thens = Vec::new_in(arena);
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after_if_thens.push((*sub_new, *current_if_then_expression));
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after_if_thens.extend(after);
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let after_if = arena.alloc(Loc::at(
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loc_expr.region,
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Expr::If(
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arena.alloc_slice_copy(after_if_thens.as_slice()),
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final_else_branch,
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),
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));
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let after_if_then = apply_task_await(
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arena,
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sub_arg.region,
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sub_arg,
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sub_pat,
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after_if,
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);
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let before_if_then = arena.alloc(Loc::at(
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loc_expr.region,
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Expr::If(before, after_if_then),
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));
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return unwrap_suffixed_expression(
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arena,
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before_if_then,
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maybe_def_pat,
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);
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}
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}
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Err(EUnwrapped::Malformed) => return Err(EUnwrapped::Malformed),
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}
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}
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}
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// check the final_else_branch
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match unwrap_suffixed_expression(arena, final_else_branch, None) {
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Ok(unwrapped_final_else) => {
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return Ok(arena.alloc(Loc::at(
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loc_expr.region,
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Expr::If(if_thens, unwrapped_final_else),
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)));
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}
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Err(EUnwrapped::UnwrappedDefExpr(..)) => {
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internal_error!("unexpected, unwrapped if-then-else Def expr should have intermediate answer as `None` was passed as pattern");
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}
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Err(EUnwrapped::UnwrappedSubExpr {
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sub_arg,
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sub_pat,
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sub_new,
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}) => {
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let ok_wrapped_return = arena.alloc(Loc::at(
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loc_expr.region,
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Expr::Apply(
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arena.alloc(Loc::at(
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loc_expr.region,
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Expr::Var {
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module_name: ModuleName::TASK,
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ident: "ok",
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suffixed: 0,
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},
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)),
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arena.alloc([sub_new]),
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CalledVia::BangSuffix,
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),
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));
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let unwrapped_final_else = apply_task_await(
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arena,
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sub_arg.region,
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sub_arg,
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sub_pat,
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ok_wrapped_return,
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);
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let new_if = arena.alloc(Loc::at(
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loc_expr.region,
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Expr::If(if_thens, unwrapped_final_else),
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));
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return unwrap_suffixed_expression(arena, new_if, maybe_def_pat);
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}
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Err(EUnwrapped::Malformed) => Err(EUnwrapped::Malformed),
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}
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}
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_ => internal_error!("unreachable, expected an If expression to desugar"),
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}
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}
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pub fn unwrap_suffixed_expression_when_help<'a>(
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