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Branch the dropLast functionality from dropAt, inserting an index gathered by subtracting 1 from the list length

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Chelsea Troy 2021-10-23 00:17:08 -05:00
parent 49a832d757
commit fd83c3b749
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4 changed files with 44 additions and 2 deletions
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39
compiler/can/src/builtins.rs
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@ -2004,6 +2004,45 @@ fn list_drop_at(symbol: Symbol, var_store: &mut VarStore) -> Def {
)
}
/// List.dropLast: List elem -> List elem
fn list_drop_last(symbol: Symbol, var_store: &mut VarStore) -> Def {
let list_var = var_store.fresh();
let body = RunLowLevel {
op: LowLevel::ListDropAt,
args: vec![
(list_var, Var(Symbol::ARG_1)),
(index_var,
// Num.sub (List.len list) 1
RunLowLevel {
op: LowLevel::NumSubWrap,
args: vec![
(
arg_var,
// List.len list
RunLowLevel {
op: LowLevel::ListLen,
args: vec![(list_var, Var(Symbol::ARG_1))],
ret_var: len_var,
},
),
(arg_var, int(num_var, num_precision_var, 1)),
],
ret_var: len_var,
},
),
],
ret_var: list_var,
};
defn(
symbol,
vec![(list_var, Symbol::ARG_1), (index_var, Symbol::ARG_2)],
var_store,
body,
list_var,
)
}
/// List.append : List elem, elem -> List elem
fn list_append(symbol: Symbol, var_store: &mut VarStore) -> Def {
let list_var = var_store.fresh();