roc/crates/compiler/can/src/effect_module.rs
2023-07-10 18:27:08 +02:00

1571 lines
47 KiB
Rust

use crate::annotation::IntroducedVariables;
use crate::def::Def;
use crate::expr::{AnnotatedMark, ClosureData, Declarations, Expr, Recursive, WhenBranchPattern};
use crate::pattern::Pattern;
use crate::scope::Scope;
use roc_collections::{SendMap, VecMap, VecSet};
use roc_module::called_via::CalledVia;
use roc_module::ident::TagName;
use roc_module::symbol::Symbol;
use roc_region::all::{Loc, Region};
use roc_types::subs::{ExhaustiveMark, RedundantMark, VarStore, Variable};
use roc_types::types::{AliasKind, LambdaSet, OptAbleType, OptAbleVar, Type, TypeExtension};
#[derive(Debug, Default, Clone, Copy)]
pub(crate) struct HostedGeneratedFunctions {
pub(crate) after: bool,
pub(crate) map: bool,
pub(crate) always: bool,
pub(crate) loop_: bool,
pub(crate) forever: bool,
}
/// the Effects alias & associated functions
///
/// A platform can define an Effect type in its header. It can have an arbitrary name
/// (e.g. Task, IO), but we'll call it an Effect in general.
///
/// From that name, we generate an effect module, an effect alias, and some functions.
///
/// The effect alias is implemented as
///
/// Effect a := {} -> a
///
/// For this alias we implement the functions specified in HostedGeneratedFunctions with the
/// standard implementation.
pub(crate) fn build_effect_builtins(
scope: &mut Scope,
effect_symbol: Symbol,
var_store: &mut VarStore,
exposed_symbols: &mut VecSet<Symbol>,
declarations: &mut Declarations,
generated_functions: HostedGeneratedFunctions,
) {
macro_rules! helper {
($f:expr) => {{
let (symbol, def) = $f(scope, effect_symbol, var_store);
// make the outside world know this symbol exists
exposed_symbols.insert(symbol);
def
}};
}
if generated_functions.after {
let def = helper!(build_effect_after);
declarations.push_def(def);
}
// Effect.map : Effect a, (a -> b) -> Effect b
if generated_functions.map {
let def = helper!(build_effect_map);
declarations.push_def(def);
}
// Effect.always : a -> Effect a
if generated_functions.always {
let def = helper!(build_effect_always);
declarations.push_def(def);
}
// Effect.forever : Effect a -> Effect b
if generated_functions.forever {
let def = helper!(build_effect_forever);
declarations.push_def(def);
}
// Effect.loop : a, (a -> Effect [Step a, Done b]) -> Effect b
if generated_functions.loop_ {
let def = helper!(build_effect_loop);
declarations.push_def(def);
}
// Useful when working on functions in this module. By default symbols that we named do now
// show up with their name. We have to register them like below to make the names show up in
// debug prints
if false {
scope.register_debug_idents();
}
}
macro_rules! new_symbol {
($scope:expr, $name:expr) => {{
$scope.introduce($name.into(), Region::zero()).unwrap()
}};
}
fn build_effect_always(
scope: &mut Scope,
effect_symbol: Symbol,
var_store: &mut VarStore,
) -> (Symbol, Def) {
// Effect.always = \value -> @Effect \{} -> value
let value_symbol = {
scope
.introduce("effect_always_value".into(), Region::zero())
.unwrap()
};
let inner_closure_symbol = {
scope
.introduce("effect_always_inner".into(), Region::zero())
.unwrap()
};
let always_symbol = { scope.introduce("always".into(), Region::zero()).unwrap() };
// \{} -> value
let const_closure = {
let arguments = vec![(
var_store.fresh(),
AnnotatedMark::new(var_store),
Loc::at_zero(empty_record_pattern(var_store)),
)];
let value_var = var_store.fresh();
let body = Expr::Var(value_symbol, value_var);
Expr::Closure(ClosureData {
function_type: var_store.fresh(),
closure_type: var_store.fresh(),
return_type: var_store.fresh(),
name: inner_closure_symbol,
captured_symbols: vec![(value_symbol, value_var)],
recursive: Recursive::NotRecursive,
arguments,
loc_body: Box::new(Loc::at_zero(body)),
})
};
// \value -> @Effect \{} -> value
let (function_var, always_closure) = {
// `@Effect \{} -> value`
let (specialized_def_type, type_arguments, lambda_set_variables) =
build_fresh_opaque_variables(var_store);
let body = Expr::OpaqueRef {
opaque_var: var_store.fresh(),
name: effect_symbol,
argument: Box::new((var_store.fresh(), Loc::at_zero(const_closure))),
specialized_def_type,
type_arguments,
lambda_set_variables,
};
let arguments = vec![(
var_store.fresh(),
AnnotatedMark::new(var_store),
Loc::at_zero(Pattern::Identifier(value_symbol)),
)];
let function_var = var_store.fresh();
let closure = Expr::Closure(ClosureData {
function_type: function_var,
closure_type: var_store.fresh(),
return_type: var_store.fresh(),
name: always_symbol,
captured_symbols: Vec::new(),
recursive: Recursive::NotRecursive,
arguments,
loc_body: Box::new(Loc::at_zero(body)),
});
(function_var, closure)
};
let mut introduced_variables = IntroducedVariables::default();
let signature = {
// Effect.always : a -> Effect a
let var_a = var_store.fresh();
introduced_variables.insert_named("a".into(), Loc::at_zero(var_a));
let effect_a = build_effect_opaque(
effect_symbol,
var_a,
Type::Variable(var_a),
var_store,
&mut introduced_variables,
);
let closure_var = var_store.fresh();
introduced_variables.insert_wildcard(Loc::at_zero(closure_var));
Type::Function(
vec![Type::Variable(var_a)],
Box::new(Type::Variable(closure_var)),
Box::new(effect_a),
)
};
let def_annotation = crate::def::Annotation {
signature,
introduced_variables,
aliases: VecMap::default(),
region: Region::zero(),
};
let pattern = Pattern::Identifier(always_symbol);
let mut pattern_vars = SendMap::default();
pattern_vars.insert(always_symbol, function_var);
let def = Def {
loc_pattern: Loc::at_zero(pattern),
loc_expr: Loc::at_zero(always_closure),
expr_var: function_var,
pattern_vars,
annotation: Some(def_annotation),
};
(always_symbol, def)
}
fn build_effect_map(
scope: &mut Scope,
effect_symbol: Symbol,
var_store: &mut VarStore,
) -> (Symbol, Def) {
// Effect.map = \@Effect thunk, mapper -> @Effect \{} -> mapper (thunk {})
let thunk_symbol = {
scope
.introduce("effect_map_thunk".into(), Region::zero())
.unwrap()
};
let thunk_var = var_store.fresh();
let mapper_symbol = {
scope
.introduce("effect_map_mapper".into(), Region::zero())
.unwrap()
};
let mapper_var = var_store.fresh();
let map_symbol = { scope.introduce("map".into(), Region::zero()).unwrap() };
// `thunk {}`
let force_thunk_call = {
let boxed = (
thunk_var,
Loc::at_zero(Expr::Var(thunk_symbol, thunk_var)),
var_store.fresh(),
var_store.fresh(),
);
let arguments = vec![(var_store.fresh(), Loc::at_zero(Expr::EmptyRecord))];
Expr::Call(Box::new(boxed), arguments, CalledVia::Space)
};
// `toEffect (thunk {})`
let mapper_call = {
let boxed = (
mapper_var,
Loc::at_zero(Expr::Var(mapper_symbol, mapper_var)),
var_store.fresh(),
var_store.fresh(),
);
let arguments = vec![(var_store.fresh(), Loc::at_zero(force_thunk_call))];
Expr::Call(Box::new(boxed), arguments, CalledVia::Space)
};
let inner_closure_symbol = {
scope
.introduce("effect_map_inner".into(), Region::zero())
.unwrap()
};
// \{} -> mapper (thunk {})
let inner_closure = {
let arguments = vec![(
var_store.fresh(),
AnnotatedMark::new(var_store),
Loc::at_zero(empty_record_pattern(var_store)),
)];
Expr::Closure(ClosureData {
function_type: var_store.fresh(),
closure_type: var_store.fresh(),
return_type: var_store.fresh(),
name: inner_closure_symbol,
captured_symbols: vec![
(thunk_symbol, var_store.fresh()),
(mapper_symbol, var_store.fresh()),
],
recursive: Recursive::NotRecursive,
arguments,
loc_body: Box::new(Loc::at_zero(mapper_call)),
})
};
// \@Effect thunk, mapper
let (specialized_def_type, type_arguments, lambda_set_variables) =
build_fresh_opaque_variables(var_store);
let arguments = vec![
(
var_store.fresh(),
AnnotatedMark::new(var_store),
Loc::at_zero(Pattern::UnwrappedOpaque {
opaque: effect_symbol,
whole_var: var_store.fresh(),
argument: Box::new((
var_store.fresh(),
Loc::at_zero(Pattern::Identifier(thunk_symbol)),
)),
specialized_def_type,
type_arguments,
lambda_set_variables,
}),
),
(
var_store.fresh(),
AnnotatedMark::new(var_store),
Loc::at_zero(Pattern::Identifier(mapper_symbol)),
),
];
// `@Effect \{} -> (mapper (thunk {}))`
let (specialized_def_type, type_arguments, lambda_set_variables) =
build_fresh_opaque_variables(var_store);
let body = Expr::OpaqueRef {
opaque_var: var_store.fresh(),
name: effect_symbol,
argument: Box::new((var_store.fresh(), Loc::at_zero(inner_closure))),
specialized_def_type,
type_arguments,
lambda_set_variables,
};
let function_var = var_store.fresh();
let map_closure = Expr::Closure(ClosureData {
function_type: function_var,
closure_type: var_store.fresh(),
return_type: var_store.fresh(),
name: map_symbol,
captured_symbols: Vec::new(),
recursive: Recursive::NotRecursive,
arguments,
loc_body: Box::new(Loc::at_zero(body)),
});
let mut introduced_variables = IntroducedVariables::default();
let signature = {
// Effect.map : Effect a, (a -> b) -> Effect b
let var_a = var_store.fresh();
let var_b = var_store.fresh();
introduced_variables.insert_named("a".into(), Loc::at_zero(var_a));
introduced_variables.insert_named("b".into(), Loc::at_zero(var_b));
let effect_a = build_effect_opaque(
effect_symbol,
var_a,
Type::Variable(var_a),
var_store,
&mut introduced_variables,
);
let effect_b = build_effect_opaque(
effect_symbol,
var_b,
Type::Variable(var_b),
var_store,
&mut introduced_variables,
);
let closure_var = var_store.fresh();
introduced_variables.insert_wildcard(Loc::at_zero(closure_var));
let a_to_b = {
Type::Function(
vec![Type::Variable(var_a)],
Box::new(Type::Variable(closure_var)),
Box::new(Type::Variable(var_b)),
)
};
let closure_var = var_store.fresh();
introduced_variables.insert_wildcard(Loc::at_zero(closure_var));
Type::Function(
vec![effect_a, a_to_b],
Box::new(Type::Variable(closure_var)),
Box::new(effect_b),
)
};
let def_annotation = crate::def::Annotation {
signature,
introduced_variables,
aliases: VecMap::default(),
region: Region::zero(),
};
let pattern = Pattern::Identifier(map_symbol);
let mut pattern_vars = SendMap::default();
pattern_vars.insert(map_symbol, function_var);
let def = Def {
loc_pattern: Loc::at_zero(pattern),
loc_expr: Loc::at_zero(map_closure),
expr_var: function_var,
pattern_vars,
annotation: Some(def_annotation),
};
(map_symbol, def)
}
fn force_thunk(expr: Expr, thunk_var: Variable, var_store: &mut VarStore) -> Expr {
let boxed = (
thunk_var,
Loc::at_zero(expr),
var_store.fresh(),
var_store.fresh(),
);
let arguments = vec![(var_store.fresh(), Loc::at_zero(Expr::EmptyRecord))];
Expr::Call(Box::new(boxed), arguments, CalledVia::Space)
}
fn build_effect_after(
scope: &mut Scope,
effect_opaque_symbol: Symbol,
var_store: &mut VarStore,
) -> (Symbol, Def) {
// Effect.after = \@Effect effect, toEffect ->
// @Effect \{} ->
// when toEffect (effect {}) is
// @Effect thunk -> thunk {}
let thunk_symbol = new_symbol!(scope, "effect_after_thunk");
let effect_symbol = new_symbol!(scope, "effect_after_effect");
let to_effect_symbol = new_symbol!(scope, "effect_after_toEffect");
let after_symbol = new_symbol!(scope, "after");
let outer_closure_symbol = new_symbol!(scope, "effect_after_inner");
// `effect {}`
let force_effect_var = var_store.fresh();
let force_effect_call = force_thunk(
Expr::Var(effect_symbol, force_effect_var),
force_effect_var,
var_store,
);
// `toEffect (effect {})`
let to_effect_var = var_store.fresh();
let to_effect_call = {
let boxed = (
to_effect_var,
Loc::at_zero(Expr::Var(to_effect_symbol, to_effect_var)),
var_store.fresh(),
var_store.fresh(),
);
let arguments = vec![(var_store.fresh(), Loc::at_zero(force_effect_call))];
Expr::Call(Box::new(boxed), arguments, CalledVia::Space)
};
// let @Effect thunk = toEffect (effect {}) in thunk {}
let let_effect_thunk = {
// `thunk {}`
let force_inner_thunk_var = var_store.fresh();
let force_inner_thunk_call = force_thunk(
Expr::Var(thunk_symbol, force_inner_thunk_var),
force_inner_thunk_var,
var_store,
);
let (specialized_def_type, type_arguments, lambda_set_variables) =
build_fresh_opaque_variables(var_store);
let pattern = Pattern::UnwrappedOpaque {
whole_var: var_store.fresh(),
opaque: effect_opaque_symbol,
argument: Box::new((
var_store.fresh(),
Loc::at_zero(Pattern::Identifier(thunk_symbol)),
)),
specialized_def_type,
type_arguments,
lambda_set_variables,
};
let pattern = WhenBranchPattern {
pattern: Loc::at_zero(pattern),
degenerate: false,
};
let branches = vec![crate::expr::WhenBranch {
guard: None,
value: Loc::at_zero(force_inner_thunk_call),
patterns: vec![pattern],
redundant: RedundantMark::new(var_store),
}];
Expr::When {
cond_var: var_store.fresh(),
branches_cond_var: var_store.fresh(),
expr_var: var_store.fresh(),
region: Region::zero(),
loc_cond: Box::new(Loc::at_zero(to_effect_call)),
branches,
exhaustive: ExhaustiveMark::new(var_store),
}
};
// @Effect \{} -> when toEffect (effect {}) is @Effect thunk -> thunk {}
let outer_effect = wrap_in_effect_thunk(
let_effect_thunk,
effect_opaque_symbol,
outer_closure_symbol,
vec![effect_symbol, to_effect_symbol],
var_store,
);
scope.register_debug_idents();
let (specialized_def_type, type_arguments, lambda_set_variables) =
build_fresh_opaque_variables(var_store);
let arguments = vec![
(
var_store.fresh(),
AnnotatedMark::new(var_store),
Loc::at_zero(Pattern::UnwrappedOpaque {
opaque: effect_opaque_symbol,
whole_var: var_store.fresh(),
argument: Box::new((
var_store.fresh(),
Loc::at_zero(Pattern::Identifier(effect_symbol)),
)),
specialized_def_type,
type_arguments,
lambda_set_variables,
}),
),
(
var_store.fresh(),
AnnotatedMark::new(var_store),
Loc::at_zero(Pattern::Identifier(to_effect_symbol)),
),
];
let function_var = var_store.fresh();
let after_closure = Expr::Closure(ClosureData {
function_type: function_var,
closure_type: var_store.fresh(),
return_type: var_store.fresh(),
name: after_symbol,
captured_symbols: Vec::new(),
recursive: Recursive::NotRecursive,
arguments,
loc_body: Box::new(Loc::at_zero(outer_effect)),
});
let mut introduced_variables = IntroducedVariables::default();
let signature = {
let var_a = var_store.fresh();
let var_b = var_store.fresh();
introduced_variables.insert_named("a".into(), Loc::at_zero(var_a));
introduced_variables.insert_named("b".into(), Loc::at_zero(var_b));
let effect_a = build_effect_opaque(
effect_opaque_symbol,
var_a,
Type::Variable(var_a),
var_store,
&mut introduced_variables,
);
let effect_b1 = build_effect_opaque(
effect_opaque_symbol,
var_b,
Type::Variable(var_b),
var_store,
&mut introduced_variables,
);
// we need a second b2 to give it a unique lambda set variable
let effect_b2 = build_effect_opaque(
effect_opaque_symbol,
var_b,
Type::Variable(var_b),
var_store,
&mut introduced_variables,
);
let closure_var = var_store.fresh();
introduced_variables.insert_lambda_set(closure_var);
let a_to_effect_b = Type::Function(
vec![Type::Variable(var_a)],
Box::new(Type::Variable(closure_var)),
Box::new(effect_b1),
);
let closure_var = var_store.fresh();
introduced_variables.insert_lambda_set(closure_var);
Type::Function(
vec![effect_a, a_to_effect_b],
Box::new(Type::Variable(closure_var)),
Box::new(effect_b2),
)
};
let def_annotation = crate::def::Annotation {
signature,
introduced_variables,
aliases: VecMap::default(),
region: Region::zero(),
};
let pattern = Pattern::Identifier(after_symbol);
let mut pattern_vars = SendMap::default();
pattern_vars.insert(after_symbol, function_var);
let def = Def {
loc_pattern: Loc::at_zero(pattern),
loc_expr: Loc::at_zero(after_closure),
expr_var: function_var,
pattern_vars,
annotation: Some(def_annotation),
};
(after_symbol, def)
}
/// turn `value` into `@Effect \{} -> value`
fn wrap_in_effect_thunk(
body: Expr,
effect_symbol: Symbol,
closure_name: Symbol,
captured_symbols: Vec<Symbol>,
var_store: &mut VarStore,
) -> Expr {
let captured_symbols: Vec<_> = captured_symbols
.into_iter()
.map(|x| (x, var_store.fresh()))
.collect();
// \{} -> body
let const_closure = {
let arguments = vec![(
var_store.fresh(),
AnnotatedMark::new(var_store),
Loc::at_zero(empty_record_pattern(var_store)),
)];
Expr::Closure(ClosureData {
function_type: var_store.fresh(),
closure_type: var_store.fresh(),
return_type: var_store.fresh(),
name: closure_name,
// captured_symbols: vec![(value_symbol, var_store.fresh())],
captured_symbols,
recursive: Recursive::NotRecursive,
arguments,
loc_body: Box::new(Loc::at_zero(body)),
})
};
// `@Effect \{} -> value`
let (specialized_def_type, type_arguments, lambda_set_variables) =
build_fresh_opaque_variables(var_store);
Expr::OpaqueRef {
opaque_var: var_store.fresh(),
name: effect_symbol,
argument: Box::new((var_store.fresh(), Loc::at_zero(const_closure))),
specialized_def_type,
type_arguments,
lambda_set_variables,
}
}
/// given `effect : Effect a`, unwrap the thunk and force it, giving a value of type `a`
fn force_effect(
effect: Expr,
effect_symbol: Symbol,
thunk_symbol: Symbol,
var_store: &mut VarStore,
) -> Expr {
let whole_var = var_store.fresh();
let thunk_var = var_store.fresh();
let (specialized_def_type, type_arguments, lambda_set_variables) =
build_fresh_opaque_variables(var_store);
let pattern = Pattern::UnwrappedOpaque {
whole_var,
opaque: effect_symbol,
argument: Box::new((thunk_var, Loc::at_zero(Pattern::Identifier(thunk_symbol)))),
specialized_def_type,
type_arguments,
lambda_set_variables,
};
let pattern_vars = SendMap::default();
// pattern_vars.insert(thunk_symbol, thunk_var);
let def = Def {
loc_pattern: Loc::at_zero(pattern),
loc_expr: Loc::at_zero(effect),
expr_var: var_store.fresh(),
pattern_vars,
annotation: None,
};
let ret_var = var_store.fresh();
let force_thunk_call = {
let thunk_var = var_store.fresh();
let boxed = (
thunk_var,
Loc::at_zero(Expr::Var(thunk_symbol, thunk_var)),
var_store.fresh(),
ret_var,
);
let arguments = vec![(var_store.fresh(), Loc::at_zero(Expr::EmptyRecord))];
let call = Expr::Call(Box::new(boxed), arguments, CalledVia::Space);
Loc::at_zero(call)
};
Expr::LetNonRec(Box::new(def), Box::new(force_thunk_call))
}
fn build_effect_forever(
scope: &mut Scope,
effect_symbol: Symbol,
var_store: &mut VarStore,
) -> (Symbol, Def) {
// morally
//
// Effect.forever = \effect -> Effect.after effect (\_ -> Effect.forever effect)
//
// Here we inline the `Effect.after`, and get
//
// Effect.forever : Effect a -> Effect b
// Effect.forever = \effect ->
// @Effect \{} ->
// @Effect thunk1 = effect
// _ = thunk1 {}
// @Effect thunk2 = Effect.forever effect
// thunk2 {}
//
// We then rely on our defunctionalization to turn this into a tail-recursive loop.
// First the `@Effect` wrapper melts away
//
// Effect.forever : ({} -> a) -> ({} -> b)
// Effect.forever = \effect ->
// \{} ->
// thunk1 = effect
// _ = thunk1 {}
// thunk2 = Effect.forever effect
// thunk2 {}
//
// Then we defunctionalize
//
// foreverInner = \{}, { effect } ->
// thunk1 = effect
// _ = thunk1 {}
// thunk2 = Effect.forever effect
// thunk2 {}
//
// Effect.forever : [C foreverInner { effect : T }]
// Effect.forever = \effect ->
// C { effect }
//
// And we have to adjust the call
//
// foreverInner = \{}, { effect } ->
// thunk1 = effect
// _ = thunk1 {}
// thunk2 = Effect.forever effect
// when thunk2 is
// C env -> foreverInner {} env.effect
//
// Making `foreverInner` perfectly tail-call optimizable
let forever_symbol = { scope.introduce("forever".into(), Region::zero()).unwrap() };
let effect = { scope.introduce("effect".into(), Region::zero()).unwrap() };
let body = build_effect_forever_body(scope, effect_symbol, forever_symbol, effect, var_store);
let arguments = vec![(
var_store.fresh(),
AnnotatedMark::new(var_store),
Loc::at_zero(Pattern::Identifier(effect)),
)];
let function_var = var_store.fresh();
let after_closure = Expr::Closure(ClosureData {
function_type: var_store.fresh(),
closure_type: var_store.fresh(),
return_type: var_store.fresh(),
name: forever_symbol,
captured_symbols: Vec::new(),
recursive: Recursive::Recursive,
arguments,
loc_body: Box::new(Loc::at_zero(body)),
});
let mut introduced_variables = IntroducedVariables::default();
let signature = {
let var_a = var_store.fresh();
let var_b = var_store.fresh();
introduced_variables.insert_named("a".into(), Loc::at_zero(var_a));
introduced_variables.insert_named("b".into(), Loc::at_zero(var_b));
let effect_a = build_effect_opaque(
effect_symbol,
var_a,
Type::Variable(var_a),
var_store,
&mut introduced_variables,
);
let effect_b = build_effect_opaque(
effect_symbol,
var_b,
Type::Variable(var_b),
var_store,
&mut introduced_variables,
);
let closure_var = var_store.fresh();
introduced_variables.insert_wildcard(Loc::at_zero(closure_var));
Type::Function(
vec![effect_a],
Box::new(Type::Variable(closure_var)),
Box::new(effect_b),
)
};
let def_annotation = crate::def::Annotation {
signature,
introduced_variables,
aliases: VecMap::default(),
region: Region::zero(),
};
let pattern = Pattern::Identifier(forever_symbol);
let mut pattern_vars = SendMap::default();
pattern_vars.insert(forever_symbol, function_var);
let def = Def {
loc_pattern: Loc::at_zero(pattern),
loc_expr: Loc::at_zero(after_closure),
expr_var: function_var,
pattern_vars,
annotation: Some(def_annotation),
};
(forever_symbol, def)
}
fn build_effect_forever_body(
scope: &mut Scope,
effect_symbol: Symbol,
forever_symbol: Symbol,
effect: Symbol,
var_store: &mut VarStore,
) -> Expr {
let closure_name = {
scope
.introduce("forever_inner".into(), Region::zero())
.unwrap()
};
let inner_body =
build_effect_forever_inner_body(scope, effect_symbol, forever_symbol, effect, var_store);
let captured_symbols = vec![effect];
wrap_in_effect_thunk(
inner_body,
effect_symbol,
closure_name,
captured_symbols,
var_store,
)
}
fn build_effect_forever_inner_body(
scope: &mut Scope,
effect_symbol: Symbol,
forever_symbol: Symbol,
effect: Symbol,
var_store: &mut VarStore,
) -> Expr {
let thunk1_var = var_store.fresh();
let thunk1_symbol = { scope.introduce("thunk1".into(), Region::zero()).unwrap() };
let thunk2_symbol = { scope.introduce("thunk2".into(), Region::zero()).unwrap() };
// @Effect thunk1 = effect
let thunk_from_effect = {
let whole_var = var_store.fresh();
let thunk_var = var_store.fresh();
let (specialized_def_type, type_arguments, lambda_set_variables) =
build_fresh_opaque_variables(var_store);
let pattern = Pattern::UnwrappedOpaque {
whole_var,
opaque: effect_symbol,
argument: Box::new((thunk_var, Loc::at_zero(Pattern::Identifier(thunk1_symbol)))),
specialized_def_type,
type_arguments,
lambda_set_variables,
};
let pattern_vars = SendMap::default();
Def {
loc_pattern: Loc::at_zero(pattern),
loc_expr: Loc::at_zero(Expr::Var(effect, var_store.fresh())),
expr_var: var_store.fresh(),
pattern_vars,
annotation: None,
}
};
// thunk1 {}
let force_thunk_call = {
let ret_var = var_store.fresh();
let boxed = (
thunk1_var,
Loc::at_zero(Expr::Var(thunk1_symbol, thunk1_var)),
var_store.fresh(),
ret_var,
);
let arguments = vec![(var_store.fresh(), Loc::at_zero(Expr::EmptyRecord))];
let call = Expr::Call(Box::new(boxed), arguments, CalledVia::Space);
Loc::at_zero(call)
};
// _ = thunk1 {}
let force_thunk1 = Def {
loc_pattern: Loc::at_zero(Pattern::Underscore),
loc_expr: force_thunk_call,
expr_var: var_store.fresh(),
pattern_vars: Default::default(),
annotation: None,
};
// recursive call `forever effect`
let forever_effect = {
let boxed = (
var_store.fresh(),
Loc::at_zero(Expr::Var(forever_symbol, var_store.fresh())),
var_store.fresh(),
var_store.fresh(),
);
let effect_var = var_store.fresh();
let arguments = vec![(effect_var, Loc::at_zero(Expr::Var(effect, effect_var)))];
Expr::Call(Box::new(boxed), arguments, CalledVia::Space)
};
// ```
// @Effect thunk2 = forever effect
// thunk2 {}
// ```
let force_thunk2 = Loc::at_zero(force_effect(
forever_effect,
effect_symbol,
thunk2_symbol,
var_store,
));
Expr::LetNonRec(
Box::new(thunk_from_effect),
Box::new(Loc::at_zero(Expr::LetNonRec(
Box::new(force_thunk1),
Box::new(force_thunk2),
))),
)
}
fn build_effect_loop(
scope: &mut Scope,
effect_symbol: Symbol,
var_store: &mut VarStore,
) -> (Symbol, Def) {
let loop_symbol = new_symbol!(scope, "loop");
let state_symbol = new_symbol!(scope, "state");
let step_symbol = new_symbol!(scope, "step");
let body = build_effect_loop_body(
scope,
effect_symbol,
loop_symbol,
state_symbol,
step_symbol,
var_store,
);
let arguments = vec![
(
var_store.fresh(),
AnnotatedMark::new(var_store),
Loc::at_zero(Pattern::Identifier(state_symbol)),
),
(
var_store.fresh(),
AnnotatedMark::new(var_store),
Loc::at_zero(Pattern::Identifier(step_symbol)),
),
];
let function_var = var_store.fresh();
let after_closure = Expr::Closure(ClosureData {
function_type: var_store.fresh(),
closure_type: var_store.fresh(),
return_type: var_store.fresh(),
name: loop_symbol,
captured_symbols: Vec::new(),
recursive: Recursive::Recursive,
arguments,
loc_body: Box::new(Loc::at_zero(body)),
});
let mut introduced_variables = IntroducedVariables::default();
let signature = {
let var_a = var_store.fresh();
let var_b = var_store.fresh();
introduced_variables.insert_named("a".into(), Loc::at_zero(var_a));
introduced_variables.insert_named("b".into(), Loc::at_zero(var_b));
let effect_b = build_effect_opaque(
effect_symbol,
var_b,
Type::Variable(var_b),
var_store,
&mut introduced_variables,
);
let state_type = {
let step_tag_name = TagName("Step".into());
let done_tag_name = TagName("Done".into());
Type::TagUnion(
vec![
(step_tag_name, vec![Type::Variable(var_a)]),
(done_tag_name, vec![Type::Variable(var_b)]),
],
TypeExtension::Closed,
)
};
let effect_state_type = {
let closure_var = var_store.fresh();
introduced_variables.insert_wildcard(Loc::at_zero(closure_var));
let actual = Type::Function(
vec![Type::EmptyRec],
Box::new(Type::Variable(closure_var)),
Box::new(state_type.clone()),
);
Type::Alias {
symbol: effect_symbol,
type_arguments: vec![OptAbleType::unbound(state_type)],
lambda_set_variables: vec![roc_types::types::LambdaSet(Type::Variable(
closure_var,
))],
infer_ext_in_output_types: vec![],
actual: Box::new(actual),
kind: AliasKind::Opaque,
}
};
let closure_var = var_store.fresh();
introduced_variables.insert_wildcard(Loc::at_zero(closure_var));
let step_type = Type::Function(
vec![Type::Variable(var_a)],
Box::new(Type::Variable(closure_var)),
Box::new(effect_state_type),
);
let closure_var = var_store.fresh();
introduced_variables.insert_wildcard(Loc::at_zero(closure_var));
Type::Function(
vec![Type::Variable(var_a), step_type],
Box::new(Type::Variable(closure_var)),
Box::new(effect_b),
)
};
let def_annotation = crate::def::Annotation {
signature,
introduced_variables,
aliases: VecMap::default(),
region: Region::zero(),
};
let pattern = Pattern::Identifier(loop_symbol);
let mut pattern_vars = SendMap::default();
pattern_vars.insert(loop_symbol, function_var);
let def = Def {
loc_pattern: Loc::at_zero(pattern),
loc_expr: Loc::at_zero(after_closure),
expr_var: function_var,
pattern_vars,
annotation: Some(def_annotation),
};
(loop_symbol, def)
}
fn build_effect_loop_body(
scope: &mut Scope,
effect_symbol: Symbol,
loop_symbol: Symbol,
state_symbol: Symbol,
step_symbol: Symbol,
var_store: &mut VarStore,
) -> Expr {
let closure_name = {
scope
.introduce("loop_inner".into(), Region::zero())
.unwrap()
};
let inner_body = build_effect_loop_inner_body(
scope,
effect_symbol,
loop_symbol,
state_symbol,
step_symbol,
var_store,
);
let captured_symbols = vec![state_symbol, step_symbol];
wrap_in_effect_thunk(
inner_body,
effect_symbol,
closure_name,
captured_symbols,
var_store,
)
}
fn applied_tag_pattern(
tag_name: TagName,
argument_symbols: &[Symbol],
var_store: &mut VarStore,
) -> Pattern {
let arguments = argument_symbols
.iter()
.map(|s| {
let pattern = Pattern::Identifier(*s);
(var_store.fresh(), Loc::at_zero(pattern))
})
.collect();
Pattern::AppliedTag {
ext_var: var_store.fresh(),
whole_var: var_store.fresh(),
tag_name,
arguments,
}
}
fn build_effect_loop_inner_body(
scope: &mut Scope,
effect_symbol: Symbol,
loop_symbol: Symbol,
state_symbol: Symbol,
step_symbol: Symbol,
var_store: &mut VarStore,
) -> Expr {
let thunk1_symbol = new_symbol!(scope, "thunk3");
let thunk2_symbol = new_symbol!(scope, "thunk4");
let new_state_symbol = new_symbol!(scope, "newState");
let done_symbol = new_symbol!(scope, "done");
// Effect thunk1 = step state
let thunk_from_effect = {
let whole_var = var_store.fresh();
let thunk_var = var_store.fresh();
let (specialized_def_type, type_arguments, lambda_set_variables) =
build_fresh_opaque_variables(var_store);
let pattern = Pattern::UnwrappedOpaque {
whole_var,
opaque: effect_symbol,
argument: Box::new((thunk_var, Loc::at_zero(Pattern::Identifier(thunk1_symbol)))),
specialized_def_type,
type_arguments,
lambda_set_variables,
};
let pattern_vars = SendMap::default();
// `step state`
let rhs = {
let step_var = var_store.fresh();
let boxed = (
step_var,
Loc::at_zero(Expr::Var(step_symbol, step_var)),
var_store.fresh(),
var_store.fresh(),
);
let state_var = var_store.fresh();
let arguments = vec![(state_var, Loc::at_zero(Expr::Var(state_symbol, state_var)))];
Expr::Call(Box::new(boxed), arguments, CalledVia::Space)
};
Def {
loc_pattern: Loc::at_zero(pattern),
loc_expr: Loc::at_zero(rhs),
expr_var: var_store.fresh(),
pattern_vars,
annotation: None,
}
};
// thunk1 {}
let force_thunk_call = {
let thunk1_var = var_store.fresh();
let ret_var = var_store.fresh();
let boxed = (
thunk1_var,
Loc::at_zero(Expr::Var(thunk1_symbol, thunk1_var)),
var_store.fresh(),
ret_var,
);
let arguments = vec![(var_store.fresh(), Loc::at_zero(Expr::EmptyRecord))];
let call = Expr::Call(Box::new(boxed), arguments, CalledVia::Space);
Loc::at_zero(call)
};
// recursive call `loop newState step`
let loop_new_state_step = {
let loop_var = var_store.fresh();
let boxed = (
loop_var,
Loc::at_zero(Expr::Var(loop_symbol, loop_var)),
var_store.fresh(),
var_store.fresh(),
);
let new_state_var = var_store.fresh();
let step_var = var_store.fresh();
let arguments = vec![
(
new_state_var,
Loc::at_zero(Expr::Var(new_state_symbol, new_state_var)),
),
(step_var, Loc::at_zero(Expr::Var(step_symbol, step_var))),
];
Expr::Call(Box::new(boxed), arguments, CalledVia::Space)
};
// ```
// @Effect thunk2 = loop effect
// thunk2 {}
// ```
let force_thunk2 = force_effect(loop_new_state_step, effect_symbol, thunk2_symbol, var_store);
let step_branch = {
let step_tag_name = TagName("Step".into());
let step_pattern = applied_tag_pattern(step_tag_name, &[new_state_symbol], var_store);
let step_pattern = WhenBranchPattern {
pattern: Loc::at_zero(step_pattern),
degenerate: false,
};
crate::expr::WhenBranch {
patterns: vec![step_pattern],
value: Loc::at_zero(force_thunk2),
guard: None,
redundant: RedundantMark::new(var_store),
}
};
let done_branch = {
let done_tag_name = TagName("Done".into());
let done_pattern = applied_tag_pattern(done_tag_name, &[done_symbol], var_store);
let done_pattern = WhenBranchPattern {
pattern: Loc::at_zero(done_pattern),
degenerate: false,
};
crate::expr::WhenBranch {
patterns: vec![done_pattern],
value: Loc::at_zero(Expr::Var(done_symbol, var_store.fresh())),
guard: None,
redundant: RedundantMark::new(var_store),
}
};
let branches = vec![step_branch, done_branch];
let match_on_force_thunk1 = Expr::When {
cond_var: var_store.fresh(),
expr_var: var_store.fresh(),
region: Region::zero(),
loc_cond: Box::new(force_thunk_call),
branches,
branches_cond_var: var_store.fresh(),
exhaustive: ExhaustiveMark::new(var_store),
};
Expr::LetNonRec(
Box::new(thunk_from_effect),
Box::new(Loc::at_zero(match_on_force_thunk1)),
)
}
pub fn build_host_exposed_def(
scope: &mut Scope,
symbol: Symbol,
ident: &str,
effect_symbol: Symbol,
var_store: &mut VarStore,
annotation: crate::annotation::Annotation,
) -> Def {
let expr_var = var_store.fresh();
let pattern = Pattern::Identifier(symbol);
let mut pattern_vars = SendMap::default();
pattern_vars.insert(symbol, expr_var);
let mut arguments: Vec<(Variable, AnnotatedMark, Loc<Pattern>)> = Vec::new();
let mut linked_symbol_arguments: Vec<(Variable, Expr)> = Vec::new();
let mut captured_symbols: Vec<(Symbol, Variable)> = Vec::new();
let crate::annotation::Annotation {
introduced_variables,
typ,
aliases,
..
} = annotation;
let def_body = {
match typ.shallow_structural_dealias() {
Type::Function(args, _, _) => {
for i in 0..args.len() {
let name = format!("closure_arg_{ident}_{i}");
let arg_symbol = {
let ident = name.clone().into();
scope.introduce(ident, Region::zero()).unwrap()
};
let arg_var = var_store.fresh();
arguments.push((
arg_var,
AnnotatedMark::new(var_store),
Loc::at_zero(Pattern::Identifier(arg_symbol)),
));
captured_symbols.push((arg_symbol, arg_var));
linked_symbol_arguments.push((arg_var, Expr::Var(arg_symbol, arg_var)));
}
let foreign_symbol_name = format!("roc_fx_{ident}");
let low_level_call = Expr::ForeignCall {
foreign_symbol: foreign_symbol_name.into(),
args: linked_symbol_arguments,
ret_var: var_store.fresh(),
};
let effect_closure_symbol = {
let name = format!("effect_closure_{ident}");
let ident = name.into();
scope.introduce(ident, Region::zero()).unwrap()
};
let effect_closure = Expr::Closure(ClosureData {
function_type: var_store.fresh(),
closure_type: var_store.fresh(),
return_type: var_store.fresh(),
name: effect_closure_symbol,
captured_symbols,
recursive: Recursive::NotRecursive,
arguments: vec![(
var_store.fresh(),
AnnotatedMark::new(var_store),
Loc::at_zero(empty_record_pattern(var_store)),
)],
loc_body: Box::new(Loc::at_zero(low_level_call)),
});
let (specialized_def_type, type_arguments, lambda_set_variables) =
build_fresh_opaque_variables(var_store);
let body = Expr::OpaqueRef {
opaque_var: var_store.fresh(),
name: effect_symbol,
argument: Box::new((var_store.fresh(), Loc::at_zero(effect_closure))),
specialized_def_type,
type_arguments,
lambda_set_variables,
};
Expr::Closure(ClosureData {
function_type: var_store.fresh(),
closure_type: var_store.fresh(),
return_type: var_store.fresh(),
name: symbol,
captured_symbols: std::vec::Vec::new(),
recursive: Recursive::NotRecursive,
arguments,
loc_body: Box::new(Loc::at_zero(body)),
})
}
_ => {
// not a function
let foreign_symbol_name = format!("roc_fx_{ident}");
let low_level_call = Expr::ForeignCall {
foreign_symbol: foreign_symbol_name.into(),
args: linked_symbol_arguments,
ret_var: var_store.fresh(),
};
let effect_closure_symbol = {
let name = format!("effect_closure_{ident}");
let ident = name.into();
scope.introduce(ident, Region::zero()).unwrap()
};
let empty_record_pattern = Pattern::RecordDestructure {
whole_var: var_store.fresh(),
ext_var: var_store.fresh(),
destructs: vec![],
};
let effect_closure = Expr::Closure(ClosureData {
function_type: var_store.fresh(),
closure_type: var_store.fresh(),
return_type: var_store.fresh(),
name: effect_closure_symbol,
captured_symbols,
recursive: Recursive::NotRecursive,
arguments: vec![(
var_store.fresh(),
AnnotatedMark::new(var_store),
Loc::at_zero(empty_record_pattern),
)],
loc_body: Box::new(Loc::at_zero(low_level_call)),
});
let (specialized_def_type, type_arguments, lambda_set_variables) =
build_fresh_opaque_variables(var_store);
Expr::OpaqueRef {
opaque_var: var_store.fresh(),
name: effect_symbol,
argument: Box::new((var_store.fresh(), Loc::at_zero(effect_closure))),
specialized_def_type,
type_arguments,
lambda_set_variables,
}
}
}
};
let def_annotation = crate::def::Annotation {
signature: typ,
introduced_variables,
aliases,
region: Region::zero(),
};
Def {
loc_pattern: Loc::at_zero(pattern),
loc_expr: Loc::at_zero(def_body),
expr_var,
pattern_vars,
annotation: Some(def_annotation),
}
}
pub fn build_effect_actual(a_type: Type, var_store: &mut VarStore) -> Type {
let closure_var = var_store.fresh();
Type::Function(
vec![Type::EmptyRec],
Box::new(Type::Variable(closure_var)),
Box::new(a_type),
)
}
/// Effect a := {} -> a
fn build_effect_opaque(
effect_symbol: Symbol,
a_var: Variable,
a_type: Type,
var_store: &mut VarStore,
introduced_variables: &mut IntroducedVariables,
) -> Type {
let closure_var = var_store.fresh();
// introduced_variables.insert_wildcard(Loc::at_zero(closure_var));
introduced_variables.insert_lambda_set(closure_var);
let actual = Type::Function(
vec![Type::EmptyRec],
Box::new(Type::Variable(closure_var)),
Box::new(a_type),
);
Type::Alias {
symbol: effect_symbol,
type_arguments: vec![OptAbleType::unbound(Type::Variable(a_var))],
lambda_set_variables: vec![roc_types::types::LambdaSet(Type::Variable(closure_var))],
infer_ext_in_output_types: vec![],
actual: Box::new(actual),
kind: AliasKind::Opaque,
}
}
fn build_fresh_opaque_variables(
var_store: &mut VarStore,
) -> (Box<Type>, Vec<OptAbleVar>, Vec<LambdaSet>) {
let closure_var = var_store.fresh();
// NB: if there are bugs, check whether not introducing variables is a problem!
// introduced_variables.insert_wildcard(Loc::at_zero(closure_var));
let a_var = var_store.fresh();
let actual = Type::Function(
vec![Type::EmptyRec],
Box::new(Type::Variable(closure_var)),
Box::new(Type::Variable(a_var)),
);
let type_arguments = vec![OptAbleVar {
var: a_var,
opt_abilities: None,
}];
let lambda_set_variables = vec![roc_types::types::LambdaSet(Type::Variable(closure_var))];
(Box::new(actual), type_arguments, lambda_set_variables)
}
#[inline(always)]
fn empty_record_pattern(var_store: &mut VarStore) -> Pattern {
Pattern::RecordDestructure {
whole_var: var_store.fresh(),
ext_var: var_store.fresh(),
destructs: vec![],
}
}