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Add unique and pivot_table functions to BuiltinsList #2005

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e875f5c
Add unique and pivot_table functions to BuiltinsList
7h3kk1d Nov 6, 2025
a6ab7e5
Remove comment
7h3kk1d Nov 20, 2025
14046c8
Fix formatting of string representation of builtins
7h3kk1d Nov 20, 2025
c7fc370
feat: add group_on_key builtin for list grouping
7h3kk1d Nov 24, 2025
a4b832d
Merge branch 'dev' into pivot_table_builtin
7h3kk1d Dec 2, 2025
32052fa
Fix string representation of builtin function
7h3kk1d Dec 5, 2025
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296 changes: 296 additions & 0 deletions src/language/builtins/BuiltinsList.re
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Original file line number Diff line number Diff line change
Expand Up @@ -2880,6 +2880,302 @@ let go: ([?], [?], [?]) -> [?] =
Fresh.(Exp.(var("zip")));
},
},
{
str: {|fix unique -> fun xs ->
fold_left(xs, fun (seen, x) -> if mem(seen, x) then seen else seen @ [x], [])|},
name: "unique",
arg: List(unknown(Internal)),
ret: List(unknown(Internal)),
imp: {
Fresh.(
Exp.(
fix_f(
Pat.var("unique"),
fn(
Pat.var("xs"),
ap(
Forward,
var("fold_left"),
tuple([
var("xs"),
fn(
Pat.tuple([Pat.var("seen"), Pat.var("x")]),
if_(
ap(
Forward,
var("mem"),
tuple([var("seen"), var("x")]),
),
var("seen"),
ap(
Forward,
var("append"),
tuple([var("seen"), list_lit([var("x")])]),
),
),
None,
None,
),
list_lit([]),
]),
),
None,
None,
),
None,
)
)
);
},
},
{
str: {hazel|fix pivot_table -> fun (table, new_col, index, value) ->
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The parameter order in the str field (table, new_col, index, value) does not match the order in the imp field at lines 3045-3049, which uses (table, new_col, index, value). However, the implementation appears to expect the parameters in the order (table, index, new_col, value) based on how they're used in the test (line 466-468: first extracts row, then column). Please verify the intended parameter order is consistent between the string representation and the implementation.

Suggested change
str: {hazel|fix pivot_table -> fun (table, new_col, index, value) ->
str: {hazel|fix pivot_table -> fun (table, index, new_col, value) ->

Copilot uses AI. Check for mistakes.
let indices = map(table, index) |> unique in
let new_cols = map(table, new_col) |> unique in

map(indices, fun idx ->
(index=idx) ...
(map(new_cols, fun col ->
(label=col,
value=filter(table, fun r -> index(r) == idx && new_col(r) == col)
|>value)
) |> from_lvs))|hazel},
name: "pivot_table",
arg:
Prod([
list(unknown(Internal)),
arrow(unknown(Internal), unknown(Internal)),
arrow(unknown(Internal), unknown(Internal)),
arrow(unknown(Internal), unknown(Internal)),
]),
ret: List(unknown(Internal)),
imp: {
open Fresh;
open Exp;
let indices =
ap(
Reverse,
var("unique"),
ap(Forward, var("map"), tuple([var("table"), var("index")])),
);
let new_cols =
ap(
Reverse,
var("unique"),
ap(
Forward,
var("map"),
tuple([var("table"), var("new_col")]),
),
);

// filter(table, fun r -> index(r) == idx && new_col(r) == col)
let filtered_values =
ap(
Forward,
var("filter"),
tuple([
var("table"),
fn(
Pat.var("r"),
bin_op(
Bool(And),
bin_op(
Poly(Equals),
ap(Forward, var("index"), var("r")),
var("idx"),
),
bin_op(
Poly(Equals),
ap(Forward, var("new_col"), var("r")),
var("col"),
),
),
None,
None,
),
]),
);
/* (label=col,
value=filter(table, fun r -> index(r) == idx && new_col(r) == col)
|>value) */
let lvs =
tuple([
tup_label(label("label"), var("col")),
tup_label(
label("value"),
ap(Forward, var("value"), filtered_values),
),
]);

let from_lvs =
ap(
Reverse,
var("from_lvs"),
ap(
Forward,
var("map"),
tuple([
var("new_cols"),
fn(Pat.var("col"), lvs, None, None),
]),
),
);

let mapped =
ap(
Forward,
var("map"),
tuple([
var("indices"),
fn(
Pat.var("idx"),
tuple_extension(
tuple([tup_label(label("index"), var("idx"))]),
from_lvs,
),
None,
None,
),
]),
);

let fn =
fn(
Pat.tuple([
Pat.var("table"),
Pat.var("new_col"),
Pat.var("index"),
Pat.var("value"),
]),
let_(
Pat.var("indices"),
indices,
let_(Pat.var("new_cols"), new_cols, mapped),
),
None,
None,
);
fix_f(Pat.var("pivot_table"), fn, None);
},
},
{
str: {|fix group_on_key -> fun (xs, f) -> fold_left(xs, fun (acc, x) ->
let update_groups = fix update_groups -> fun (acc, key, x) ->
case acc
| [] => [(key, [x])]
| (k, g) :: acc => if k == key then (k, x :: g) :: acc else (k, g) :: update_groups(acc, key, x)
end in update_groups(acc, f(x), x), [])|},
name: "group_on_key",
arg:
Prod([
list(unknown(Internal)),
arrow(unknown(Internal), unknown(Internal)),
]),
ret: List(prod([unknown(Internal), list(unknown(Internal))])),
imp: {
Fresh.(
Exp.(
fix_f(
Pat.var("group_on_key"),
fn(
Pat.tuple([Pat.var("xs"), Pat.var("f")]),
ap(
Forward,
var("fold_left"),
tuple([
var("xs"),
let_(
Pat.var("update_groups"),
fix_f(
Pat.var("update_groups"),
fn(
Pat.tuple([
Pat.var("acc"),
Pat.var("key"),
Pat.var("x"),
]),
match(
var("acc"),
[
(
Pat.list_lit([]),
list_lit([
tuple([
var("key"),
list_lit([var("x")]),
]),
]),
),
(
Pat.cons(
Pat.tuple([Pat.var("k"), Pat.var("g")]),
Pat.var("acc_tail"),
),
if_(
bin_op(
Poly(Equals),
var("k"),
var("key"),
),
cons(
tuple([
var("k"),
list_concat(
var("g"),
list_lit([var("x")]),
),
]),
var("acc_tail"),
),
cons(
tuple([var("k"), var("g")]),
ap(
Forward,
var("update_groups"),
tuple([
var("acc_tail"),
var("key"),
var("x"),
]),
),
),
),
),
],
),
None,
Some("update_groups+"),
),
None,
),
fn(
Pat.tuple([Pat.var("acc"), Pat.var("x")]),
ap(
Forward,
var("update_groups"),
tuple([
var("acc"),
ap(Forward, var("f"), var("x")),
var("x"),
]),
),
None,
None,
),
),
list_lit([]),
]),
),
None,
Some("group_on_key+"),
),
None,
)
)
);
},
},
]
// De-alias all aliases
|> Util.ListUtil.map_with_history((prev, curr) =>
Expand Down
30 changes: 30 additions & 0 deletions test/evaluator/Test_Evaluator_Builtins_Lists.re
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Original file line number Diff line number Diff line change
Expand Up @@ -446,5 +446,35 @@ let tests = (
);
},
),
test_case("unique", `Quick, () =>
parse_and_evaluate_test({|[1, 2, 3]|}, {|unique([1, 2, 2, 3, 1, 3])|})
),
test_case("group_on_key by parity", `Quick, () =>
parse_and_evaluate_test(
{|[(1, [1, 3]), (0, [2, 4])]|},
{|group_on_key([1, 2, 3, 4], fun x -> int_mod(x, 2))|},
)
),
test_case("pivot_table", `Quick, () =>
parse_and_evaluate_test(
{|
[(index="x", `A`=2, `B`=1, `C`=0), (index="y", `A`=1, `B`=1, `C`=1)]
|},
{|pivot_table(
[
("A", "x"),
("A", "y"),
("B", "x"),
("B", "y"),
("A", "x"),
("C", "y")
],
fun (r, _) -> r,
fun (_, c) -> c,
length
)
|},
)
),
],
);