Add to arg to all_equal

Resolves   #817.

DOCS.md

@@ -4210,9 +4210,15 @@ _Can't be done without the definition of `windowsof`; see the compiled header fo
 
 #### `all_equal`
 
-**all\_equal**(_iterable_)
+**all\_equal**(_iterable_, _to_=`...`)
 
-Coconut's `all_equal` built-in takes in an iterable and determines whether all of its elements are equal to each other. `all_equal` assumes transitivity of equality and that `!=` is the negation of `==`. Special support is provided for [`numpy`](#numpy-integration) objects.
+Coconut's `all_equal` built-in takes in an iterable and determines whether all of its elements are equal to each other.
+
+If _to_ is passed, `all_equal` will check that all the elements are specifically equal to that value, rather than just equal to each other.
+
+Note that `all_equal` assumes transitivity of equality, that `!=` is the negation of `==`, and that empty arrays always have all their elements equal.
+
+Special support is provided for [`numpy`](#numpy-integration) objects.
 
 ##### Example
 

__coconut__/__init__.pyi

@@ -1680,7 +1680,7 @@ def lift_apart(func: _t.Callable[..., _W]) -> _t.Callable[..., _t.Callable[...,
     ...
 
 
-def all_equal(iterable: _Iterable) -> bool:
+def all_equal(iterable: _t.Iterable[_T], to: _T = ...) -> bool:
     """For a given iterable, check whether all elements in that iterable are equal to each other.
 
     Supports numpy arrays. Assumes transitivity and 'x != y' being equivalent to 'not (x == y)'.

coconut/compiler/templates/header.py_template

@@ -1953,8 +1953,9 @@ class lift_apart(lift):
     lift_apart also supports a shortcut form such that lift_apart(f, *func_args, **func_kwargs) is equivalent to lift_apart(f)(*func_args, **func_kwargs).
     """
     _apart = True
-def all_equal(iterable):
+def all_equal(iterable, to=_coconut_sentinel):
     """For a given iterable, check whether all elements in that iterable are equal to each other.
+    If 'to' is passed, check that all the elements are equal to that value.
 
     Supports numpy arrays. Assumes transitivity and 'x != y' being equivalent to 'not (x == y)'.
     """
@@ -1964,8 +1965,8 @@ def all_equal(iterable):
             iterable = _coconut_xarray_to_numpy(iterable)
         elif iterable_module in _coconut.pandas_modules:
             iterable = iterable.to_numpy()
-        return not _coconut.len(iterable) or (iterable == iterable[0]).all()
-    first_item = _coconut_sentinel
+        return not _coconut.len(iterable) or (iterable == (iterable[0] if to is _coconut_sentinel else to)).all()
+    first_item = to
     for item in iterable:
         if first_item is _coconut_sentinel:
             first_item = item

coconut/root.py

@@ -26,7 +26,7 @@
 VERSION = "3.0.4"
 VERSION_NAME = None
 # False for release, int >= 1 for develop
-DEVELOP = 10
+DEVELOP = 11
 ALPHA = False  # for pre releases rather than post releases
 
 assert DEVELOP is False or DEVELOP >= 1, "DEVELOP must be False or an int >= 1"

coconut/tests/src/cocotest/agnostic/primary_2.coco

@@ -421,6 +421,9 @@ def primary_test_2() -> bool:
     arr |>= [[3; 4] ;; .]
     assert arr == [3; 4;; 1; 2] == [[3; 4] ;; .] |> call$(?, [. ; 2] |> call$(?, 1))
     assert (if)(10, 20, 30) == 20 == (if)(0, 10, 20)
+    assert all_equal([], to=10)
+    assert all_equal([10; 10; 10; 10], to=10)
+    assert not all_equal([1, 1], to=10)
 
     with process_map.multiple_sequential_calls():  # type: ignore
         assert map((+), range(3), range(4)$[:-1], strict=True) |> list == [0, 2, 4] == process_map((+), range(3), range(4)$[:-1], strict=True) |> list  # type: ignore

coconut/tests/src/extras.coco

@@ -604,6 +604,9 @@ def test_numpy() -> bool:
     assert all_equal(np.array([1, 1]))
     assert all_equal(np.array([1, 1;; 1, 1]))
     assert not all_equal(np.array([1, 1;; 1, 2]))
+    assert all_equal(np.array([]), to=10)
+    assert all_equal(np.array([10; 10;; 10; 10]), to=10)
+    assert not all_equal(np.array([1, 1]), to=10)
     assert (
         cartesian_product(np.array([1, 2]), np.array([3, 4]))
         `np.array_equal`