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Add List.max builtin

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Chelsea Troy 2021-10-30 19:17:35 -05:00
parent c76d672363
commit 4afaf96aea
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131
compiler/can/src/builtins.rs
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@ -81,6 +81,7 @@ pub fn builtin_defs_map(symbol: Symbol, var_store: &mut VarStore) -> Option<Def>
LIST_CONCAT => list_concat,
LIST_CONTAINS => list_contains,
LIST_MIN => list_min,
LIST_MAX => list_max,
LIST_SUM => list_sum,
LIST_PRODUCT => list_product,
LIST_PREPEND => list_prepend,
@ -2268,6 +2269,136 @@ fn list_min_lt(list_elem_var: Variable, var_store: &mut VarStore) -> Expr {
)
}
// max : List (Num a) -> Result (Num a) [ ListWasEmpty ]*
fn list_max(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_max_gt(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_max_gt(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::NumGt,
args: vec![
(list_elem_var, Var(Symbol::ARG_4)),
(list_elem_var, Var(Symbol::ARG_3)),
],
ret_var: bool_var,
},
),
// return elem
no_region(Var(Symbol::ARG_4)),
)],
// return acc
final_else: Box::new(no_region(Var(Symbol::ARG_3))),
};
defn_help(
Symbol::LIST_MAX_GT,
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();