Fix the issue using __radd__

Author: hbierlee

crates/pyndakaas/python/pindakaas/__init__.py

@@ -1,7 +1,7 @@
 import pindakaas.solver
 
 from .encoding import CNF, WCNF, ClauseDatabase, Constraint
-from .pindakaas import Formula, Lit, Encoder, BoolLinExp
+from .pindakaas import Formula, Lit, Encoder
 
 __doc__ = pindakaas.__doc__
 __all__ = ["Constraint", "ClauseDatabase", "CNF", "Encoder", "Formula", "Lit", "WCNF"]

crates/pyndakaas/python/tests/test_modelling.py

@@ -4,14 +4,14 @@
 def test_bool_lin():
     f = pindakaas.CNF()
     x, y, z = f.new_vars(3)
+    assert str(x + 2) == "x₁ + 2"
+    assert str(2 + x) == "x₁ + 2"
     c = x + y - z + 2
     assert str(c) == "-x₃ + x₂ + x₁ + 2"
-    c = sum([x, y, z], pindakaas.BoolLinExp())
+    c = sum([x, y, z])
     assert str(c) == "x₃ + x₂ + x₁"
-    c = sum([y, y, z], x)
-    assert str(c) == "x₃ + x₂ + x₂ + x₁"
     c *= 2
-    assert str(c) == "2*x₃ + 2*x₂ + 2*x₂ + 2*x₁"
+    assert str(c) == "2*x₃ + 2*x₂ + 2*x₁"
     c = x + y + z
     d = c == 2
     assert str(d) == "x₃ + x₂ + x₁ == 2"

crates/pyndakaas/src/lib.rs

@@ -412,6 +412,10 @@ mod pindakaas {
 			self.as_bool_lin_exp().__add__(other)
 		}
 
+		fn __radd__(&self, other: i64) -> BoolLinExp {
+			self.as_bool_lin_exp().__add__(BoolLinArg::Int(other))
+		}
+
 		fn __and__(&self, other: FormulaArg) -> Formula {
 			Formula(self.as_formula()).__and__(other)
 		}