Add (if) op

Resolves #813.

__coconut__/__init__.pyi

@@ -1216,6 +1216,11 @@ def _coconut_comma_op(*args: _t.Any) -> _Tuple:
     ...
 
 
+def _coconut_if_op(cond: _t.Any, if_true: _T, if_false: _U) -> _t.Union[_T, _U]:
+    """If operator (if). Equivalent to (cond, if_true, if_false) => if_true if cond else if_false."""
+    ...
+
+
 if sys.version_info < (3, 5):
     @_t.overload
     def _coconut_matmul(a: _T, b: _T) -> _T: ...

coconut/__coconut__.pyi

@@ -1,2 +1,2 @@
 from __coconut__ import *
-from __coconut__ import _coconut_tail_call, _coconut_tco, _coconut_call_set_names, _coconut_handle_cls_kwargs, _coconut_handle_cls_stargs, _namedtuple_of, _coconut, _coconut_Expected, _coconut_MatchError, _coconut_SupportsAdd, _coconut_SupportsMinus, _coconut_SupportsMul, _coconut_SupportsPow, _coconut_SupportsTruediv, _coconut_SupportsFloordiv, _coconut_SupportsMod, _coconut_SupportsAnd, _coconut_SupportsXor, _coconut_SupportsOr, _coconut_SupportsLshift, _coconut_SupportsRshift, _coconut_SupportsMatmul, _coconut_SupportsInv, _coconut_Expected, _coconut_MatchError, _coconut_iter_getitem, _coconut_base_compose, _coconut_forward_compose, _coconut_back_compose, _coconut_forward_star_compose, _coconut_back_star_compose, _coconut_forward_dubstar_compose, _coconut_back_dubstar_compose, _coconut_pipe, _coconut_star_pipe, _coconut_dubstar_pipe, _coconut_back_pipe, _coconut_back_star_pipe, _coconut_back_dubstar_pipe, _coconut_none_pipe, _coconut_none_star_pipe, _coconut_none_dubstar_pipe, _coconut_bool_and, _coconut_bool_or, _coconut_none_coalesce, _coconut_minus, _coconut_map, _coconut_partial, _coconut_complex_partial, _coconut_get_function_match_error, _coconut_base_pattern_func, _coconut_addpattern, _coconut_sentinel, _coconut_assert, _coconut_raise, _coconut_mark_as_match, _coconut_reiterable, _coconut_self_match_types, _coconut_dict_merge, _coconut_exec, _coconut_comma_op, _coconut_arr_concat_op, _coconut_mk_anon_namedtuple, _coconut_matmul, _coconut_py_str, _coconut_flatten, _coconut_multiset, _coconut_back_none_pipe, _coconut_back_none_star_pipe, _coconut_back_none_dubstar_pipe, _coconut_forward_none_compose, _coconut_back_none_compose, _coconut_forward_none_star_compose, _coconut_back_none_star_compose, _coconut_forward_none_dubstar_compose, _coconut_back_none_dubstar_compose, _coconut_call_or_coefficient, _coconut_in, _coconut_not_in, _coconut_attritemgetter
+from __coconut__ import _coconut_tail_call, _coconut_tco, _coconut_call_set_names, _coconut_handle_cls_kwargs, _coconut_handle_cls_stargs, _namedtuple_of, _coconut, _coconut_Expected, _coconut_MatchError, _coconut_SupportsAdd, _coconut_SupportsMinus, _coconut_SupportsMul, _coconut_SupportsPow, _coconut_SupportsTruediv, _coconut_SupportsFloordiv, _coconut_SupportsMod, _coconut_SupportsAnd, _coconut_SupportsXor, _coconut_SupportsOr, _coconut_SupportsLshift, _coconut_SupportsRshift, _coconut_SupportsMatmul, _coconut_SupportsInv, _coconut_Expected, _coconut_MatchError, _coconut_iter_getitem, _coconut_base_compose, _coconut_forward_compose, _coconut_back_compose, _coconut_forward_star_compose, _coconut_back_star_compose, _coconut_forward_dubstar_compose, _coconut_back_dubstar_compose, _coconut_pipe, _coconut_star_pipe, _coconut_dubstar_pipe, _coconut_back_pipe, _coconut_back_star_pipe, _coconut_back_dubstar_pipe, _coconut_none_pipe, _coconut_none_star_pipe, _coconut_none_dubstar_pipe, _coconut_bool_and, _coconut_bool_or, _coconut_none_coalesce, _coconut_minus, _coconut_map, _coconut_partial, _coconut_complex_partial, _coconut_get_function_match_error, _coconut_base_pattern_func, _coconut_addpattern, _coconut_sentinel, _coconut_assert, _coconut_raise, _coconut_mark_as_match, _coconut_reiterable, _coconut_self_match_types, _coconut_dict_merge, _coconut_exec, _coconut_comma_op, _coconut_arr_concat_op, _coconut_mk_anon_namedtuple, _coconut_matmul, _coconut_py_str, _coconut_flatten, _coconut_multiset, _coconut_back_none_pipe, _coconut_back_none_star_pipe, _coconut_back_none_dubstar_pipe, _coconut_forward_none_compose, _coconut_back_none_compose, _coconut_forward_none_star_compose, _coconut_back_none_star_compose, _coconut_forward_none_dubstar_compose, _coconut_back_none_dubstar_compose, _coconut_call_or_coefficient, _coconut_in, _coconut_not_in, _coconut_attritemgetter, _coconut_if_op

coconut/compiler/grammar.py

@@ -1067,6 +1067,7 @@ class Grammar(object):
             | fixto(dollar, "_coconut_partial")
             | fixto(keyword("assert"), "_coconut_assert")
             | fixto(keyword("raise"), "_coconut_raise")
+            | fixto(keyword("if"), "_coconut_if_op")
             | fixto(keyword("is") + keyword("not"), "_coconut.operator.is_not")
             | fixto(keyword("not") + keyword("in"), "_coconut_not_in")
 

coconut/compiler/header.py

@@ -639,7 +639,7 @@ def __anext__(self):
     #  (extra_format_dict is to keep indentation levels matching)
     extra_format_dict = dict(
         # when anything is added to this list it must also be added to *both* __coconut__ stub files
-        underscore_imports="{tco_comma}{call_set_names_comma}{handle_cls_args_comma}_namedtuple_of, _coconut, _coconut_Expected, _coconut_MatchError, _coconut_SupportsAdd, _coconut_SupportsMinus, _coconut_SupportsMul, _coconut_SupportsPow, _coconut_SupportsTruediv, _coconut_SupportsFloordiv, _coconut_SupportsMod, _coconut_SupportsAnd, _coconut_SupportsXor, _coconut_SupportsOr, _coconut_SupportsLshift, _coconut_SupportsRshift, _coconut_SupportsMatmul, _coconut_SupportsInv, _coconut_iter_getitem, _coconut_base_compose, _coconut_forward_compose, _coconut_back_compose, _coconut_forward_star_compose, _coconut_back_star_compose, _coconut_forward_dubstar_compose, _coconut_back_dubstar_compose, _coconut_pipe, _coconut_star_pipe, _coconut_dubstar_pipe, _coconut_back_pipe, _coconut_back_star_pipe, _coconut_back_dubstar_pipe, _coconut_none_pipe, _coconut_none_star_pipe, _coconut_none_dubstar_pipe, _coconut_bool_and, _coconut_bool_or, _coconut_none_coalesce, _coconut_minus, _coconut_map, _coconut_partial, _coconut_complex_partial, _coconut_get_function_match_error, _coconut_base_pattern_func, _coconut_addpattern, _coconut_sentinel, _coconut_assert, _coconut_raise, _coconut_mark_as_match, _coconut_reiterable, _coconut_self_match_types, _coconut_dict_merge, _coconut_exec, _coconut_comma_op, _coconut_arr_concat_op, _coconut_mk_anon_namedtuple, _coconut_matmul, _coconut_py_str, _coconut_flatten, _coconut_multiset, _coconut_back_none_pipe, _coconut_back_none_star_pipe, _coconut_back_none_dubstar_pipe, _coconut_forward_none_compose, _coconut_back_none_compose, _coconut_forward_none_star_compose, _coconut_back_none_star_compose, _coconut_forward_none_dubstar_compose, _coconut_back_none_dubstar_compose, _coconut_call_or_coefficient, _coconut_in, _coconut_not_in, _coconut_attritemgetter".format(**format_dict),
+        underscore_imports="{tco_comma}{call_set_names_comma}{handle_cls_args_comma}_namedtuple_of, _coconut, _coconut_Expected, _coconut_MatchError, _coconut_SupportsAdd, _coconut_SupportsMinus, _coconut_SupportsMul, _coconut_SupportsPow, _coconut_SupportsTruediv, _coconut_SupportsFloordiv, _coconut_SupportsMod, _coconut_SupportsAnd, _coconut_SupportsXor, _coconut_SupportsOr, _coconut_SupportsLshift, _coconut_SupportsRshift, _coconut_SupportsMatmul, _coconut_SupportsInv, _coconut_iter_getitem, _coconut_base_compose, _coconut_forward_compose, _coconut_back_compose, _coconut_forward_star_compose, _coconut_back_star_compose, _coconut_forward_dubstar_compose, _coconut_back_dubstar_compose, _coconut_pipe, _coconut_star_pipe, _coconut_dubstar_pipe, _coconut_back_pipe, _coconut_back_star_pipe, _coconut_back_dubstar_pipe, _coconut_none_pipe, _coconut_none_star_pipe, _coconut_none_dubstar_pipe, _coconut_bool_and, _coconut_bool_or, _coconut_none_coalesce, _coconut_minus, _coconut_map, _coconut_partial, _coconut_complex_partial, _coconut_get_function_match_error, _coconut_base_pattern_func, _coconut_addpattern, _coconut_sentinel, _coconut_assert, _coconut_raise, _coconut_mark_as_match, _coconut_reiterable, _coconut_self_match_types, _coconut_dict_merge, _coconut_exec, _coconut_comma_op, _coconut_arr_concat_op, _coconut_mk_anon_namedtuple, _coconut_matmul, _coconut_py_str, _coconut_flatten, _coconut_multiset, _coconut_back_none_pipe, _coconut_back_none_star_pipe, _coconut_back_none_dubstar_pipe, _coconut_forward_none_compose, _coconut_back_none_compose, _coconut_forward_none_star_compose, _coconut_back_none_star_compose, _coconut_forward_none_dubstar_compose, _coconut_back_none_dubstar_compose, _coconut_call_or_coefficient, _coconut_in, _coconut_not_in, _coconut_attritemgetter, _coconut_if_op".format(**format_dict),
         import_typing=pycondition(
             (3, 5),
             if_ge='''

coconut/compiler/templates/header.py_template

@@ -585,6 +585,9 @@ def _coconut_minus(a, b=_coconut_sentinel):
 def _coconut_comma_op(*args):
     """Comma operator (,). Equivalent to (*args) => args."""
     return args
+def _coconut_if_op(cond, if_true, if_false):
+    """If operator (if). Equivalent to (cond, if_true, if_false) => if_true if cond else if_false."""
+    return if_true if cond else if_false
 {def_coconut_matmul}
 class scan(_coconut_has_iter):
     """Reduce func over iterable, yielding intermediate results,

coconut/root.py

@@ -26,7 +26,7 @@
 VERSION = "3.0.4"
 VERSION_NAME = None
 # False for release, int >= 1 for develop
-DEVELOP = 8
+DEVELOP = 9
 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

@@ -420,6 +420,7 @@ def primary_test_2() -> bool:
     arr |>= [. ; 2]
     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)
 
     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