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add builtin List.min

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This commit is contained in:
Tim Whiting 2021-10-27 20:28:34 -06:00
parent d7083d5daf
commit c721a1cc1f
4 changed files with 159 additions and 1 deletions
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9
compiler/builtins/src/std.rs
View file

@ -722,7 +722,7 @@ pub fn types() -> MutMap<Symbol, (SolvedType, Region)> {
add_top_level_function_type!(
Symbol::LIST_LAST,
vec![list_type(flex(TVAR1))],
Box::new(result_type(flex(TVAR1), list_was_empty)),
Box::new(result_type(flex(TVAR1), list_was_empty.clone())),
);
// set : List elem, Nat, elem -> List elem
@ -746,6 +746,13 @@ pub fn types() -> MutMap<Symbol, (SolvedType, Region)> {
Box::new(bool_type()),
);
// min : List (Num a) -> Result (Num a) [ ListWasEmpty ]*
add_top_level_function_type!(
Symbol::LIST_MIN,
vec![list_type(num_type(flex(TVAR1)))],
Box::new(result_type(num_type(flex(TVAR1)), list_was_empty)),
);
// sum : List (Num a) -> Num a
add_top_level_function_type!(
Symbol::LIST_SUM,

124
compiler/can/src/builtins.rs
View file

@ -79,6 +79,7 @@ pub fn builtin_defs_map(symbol: Symbol, var_store: &mut VarStore) -> Option<Def>
LIST_REVERSE => list_reverse,
LIST_CONCAT => list_concat,
LIST_CONTAINS => list_contains,
LIST_MIN => list_min,
LIST_SUM => list_sum,
LIST_PRODUCT => list_product,
LIST_PREPEND => list_prepend,
@ -2131,6 +2132,129 @@ fn list_walk_until(symbol: Symbol, var_store: &mut VarStore) -> Def {
lowlevel_3(symbol, LowLevel::ListWalkUntil, var_store)
}
// min : List (Num a) -> Result (Num a) [ ListWasEmpty ]*
fn list_min(symbol: Symbol, var_store: &mut VarStore) -> Def {
let arg_var = var_store.fresh();
let bool_var = var_store.fresh();
let list_var = var_store.fresh();
let len_var = Variable::NAT;
let num_var = len_var;
let num_precision_var = Variable::NATURAL;
let list_elem_var = var_store.fresh();
let ret_var = var_store.fresh();
let closure_var = var_store.fresh();
// Perform a bounds check. If it passes, delegate to List.getUnsafe.
let body = If {
cond_var: bool_var,
branch_var: var_store.fresh(),
branches: vec![(
// if-condition
no_region(
// List.len list != 0
RunLowLevel {
op: LowLevel::NotEq,
args: vec![
(len_var, int(num_var, num_precision_var, 0)),
(
len_var,
RunLowLevel {
op: LowLevel::ListLen,
args: vec![(list_var, Var(Symbol::ARG_1))],
ret_var: len_var,
},
),
],
ret_var: bool_var,
},
),
// list was not empty
no_region(
// Ok ( List.walk list (List.getUnsafe list 0) \acc,elem -> if elem < acc then elem else acc )
tag(
"Ok",
vec![
// List.walk list (List.getUnsafe list 0) \acc,elem -> if elem < acc then elem else acc
RunLowLevel {
op: LowLevel::ListWalk,
args: vec![
(list_var, Var(Symbol::ARG_1)),
// (List.getUnsafe list 0)
(
list_elem_var,
RunLowLevel {
op: LowLevel::ListGetUnsafe,
args: vec![
(list_var, Var(Symbol::ARG_1)),
(arg_var, int(num_var, num_precision_var, 0)),
],
ret_var: list_elem_var,
},
),
// \acc,elem -> if elem < acc then elem else acc
(closure_var, list_min_lt(list_elem_var, var_store)),
],
ret_var: list_elem_var,
},
],
var_store,
),
),
)],
final_else: Box::new(
// list was empty
no_region(
// Err ListWasEmpty
tag(
"Err",
vec![tag("ListWasEmpty", Vec::new(), var_store)],
var_store,
),
),
),
};
defn(
symbol,
vec![(list_var, Symbol::ARG_1)],
var_store,
body,
ret_var,
)
}
// \acc,elem -> if elem < acc then elem else acc
fn list_min_lt(list_elem_var: Variable, var_store: &mut VarStore) -> Expr {
let bool_var = var_store.fresh();
// if elem < acc then elem else acc
let body = If {
cond_var: bool_var,
branch_var: list_elem_var,
branches: vec![(
// if-condition
no_region(
// elem < acc
RunLowLevel {
op: LowLevel::NumLt,
args: vec![(list_elem_var, Var(Symbol::ARG_4)), (list_elem_var, Var(Symbol::ARG_3))],
ret_var: bool_var,
},
),
// list was not empty
no_region(Var(Symbol::ARG_4)),
)],
final_else: Box::new(no_region(Var(Symbol::ARG_3))),
};
defn_help(
Symbol::LIST_MIN_LT,
vec![(list_elem_var, Symbol::ARG_3), (list_elem_var, Symbol::ARG_4)],
var_store,
body,
list_elem_var,
)
}
/// List.sum : List (Num a) -> Num a
fn list_sum(symbol: Symbol, var_store: &mut VarStore) -> Def {
let num_var = var_store.fresh();

2
compiler/module/src/symbol.rs
View file

@ -1053,6 +1053,8 @@ define_builtins! {
33 LIST_SWAP: "swap"
34 LIST_DROP_AT: "dropAt"
35 LIST_DROP_LAST: "dropLast"
36 LIST_MIN: "min"
37 LIST_MIN_LT: "#minlt"
}
5 RESULT: "Result" => {
0 RESULT_RESULT: "Result" imported // the Result.Result type alias

25
compiler/test_gen/src/gen_list.rs
View file

@ -1949,6 +1949,31 @@ fn list_contains() {
assert_evals_to!(indoc!("List.contains [] 4"), false, bool);
}
#[test]
fn list_min() {
assert_evals_to!(
indoc!(
r#"
when List.min [] is
Ok val -> val
Err _ -> -1
"#
),
-1,
i64
);
assert_evals_to!(
indoc!(
r#"
when List.min [3, 1, 2] is
Ok val -> val
Err _ -> -1
"#
),
1,
i64
);
}
#[test]
fn list_sum() {