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Implement List.dropIf

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This was referenced in the `List` documentation and in the
[tutorial](./TUTORIAL.md), but wasn't actually implemented prior to this
commit!

Part of #2227
This commit is contained in:
ayazhafiz 2021-12-22 12:33:08 -06:00
parent 78a247e6f2
commit ed64ff912a
5 changed files with 180 additions and 1 deletions
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57
compiler/can/src/builtins.rs
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@ -113,6 +113,7 @@ pub fn builtin_defs_map(symbol: Symbol, var_store: &mut VarStore) -> Option<Def>
LIST_DROP => list_drop,
LIST_DROP_AT => list_drop_at,
LIST_DROP_FIRST => list_drop_first,
LIST_DROP_IF => list_drop_if,
LIST_DROP_LAST => list_drop_last,
LIST_SWAP => list_swap,
LIST_MAP_WITH_INDEX => list_map_with_index,
@ -2482,6 +2483,7 @@ fn list_drop_at(symbol: Symbol, var_store: &mut VarStore) -> Def {
)
}
/// List.dropFirst : List elem -> Result { first: elem, others : List elem } [ ListWasEmpty ]*
fn list_drop_first(symbol: Symbol, var_store: &mut VarStore) -> Def {
let list_var = var_store.fresh();
let index_var = var_store.fresh();
@ -2506,6 +2508,61 @@ fn list_drop_first(symbol: Symbol, var_store: &mut VarStore) -> Def {
)
}
/// List.dropIf : List elem, (elem -> Bool) -> List elem
fn list_drop_if(symbol: Symbol, var_store: &mut VarStore) -> Def {
let sym_list = Symbol::ARG_1;
let sym_predicate = Symbol::ARG_2;
let t_list = var_store.fresh();
let t_predicate = var_store.fresh();
let t_keep_predicate = var_store.fresh();
let t_elem = var_store.fresh();
// Defer to keepIf for implementation
// List.dropIf l p = List.keepIf l (\e -> Bool.not (p e))
let keep_predicate = Closure(ClosureData {
function_type: t_keep_predicate,
closure_type: var_store.fresh(),
closure_ext_var: var_store.fresh(),
return_type: Variable::BOOL,
name: Symbol::LIST_DROP_IF_PREDICATE,
recursive: Recursive::NotRecursive,
captured_symbols: vec![(sym_predicate, t_predicate)],
arguments: vec![(t_elem, no_region(Pattern::Identifier(Symbol::ARG_3)))],
loc_body: {
let should_drop = Call(
Box::new((
t_predicate,
no_region(Var(sym_predicate)),
var_store.fresh(),
Variable::BOOL,
)),
vec![(t_elem, no_region(Var(Symbol::ARG_3)))],
CalledVia::Space,
);
Box::new(no_region(RunLowLevel {
op: LowLevel::Not,
args: vec![(Variable::BOOL, should_drop)],
ret_var: Variable::BOOL,
}))
},
});
let body = RunLowLevel {
op: LowLevel::ListKeepIf,
args: vec![(t_list, Var(sym_list)), (t_keep_predicate, keep_predicate)],
ret_var: t_list,
};
defn(
symbol,
vec![(t_list, sym_list), (t_predicate, sym_predicate)],
var_store,
body,
t_list,
)
}
/// List.dropLast: List elem -> List elem
fn list_drop_last(symbol: Symbol, var_store: &mut VarStore) -> Def {
let list_var = var_store.fresh();