Remove "returns" dependency

elite_engineering/materials.py

@@ -3,8 +3,6 @@ import enum
 import fractions
 import typing
 
-from returns.maybe import Maybe, Some, Nothing
-
 from elite_engineering import trade
 
 
@@ -157,9 +155,9 @@ class Material:
 
     MAX_CAPACITY: int = 300
 
-    def trade_ratio(self, other: "Material") -> Maybe[fractions.Fraction]:
+    def trade_ratio(self, other: "Material") -> typing.Optional[fractions.Fraction]:
         if self.type_ != other.type_:
-            return Nothing
+            return None
         return trade.ratio(self.grade, other.grade, self.category != other.category)
 
 

elite_engineering/trade.py

@@ -1,13 +1,12 @@
 import fractions
-
-from returns.maybe import Maybe, Nothing, Some
+import typing
 
 MAX_CAPACITY: int = 300
 
 
 def ratio(
     grade_in: int, grade_out: int, across_categories: bool
-) -> Maybe[fractions.Fraction]:
+) -> typing.Optional[fractions.Fraction]:
     trading_up = grade_out > grade_in
     grade_base = 6 if trading_up else 3
     grade_ratio = fractions.Fraction(grade_base ** grade_out, grade_base ** grade_in)
@@ -16,6 +15,6 @@ def ratio(
     )
     result = grade_ratio * category_ratio
     if max(result.numerator, result.denominator) > MAX_CAPACITY:
-        return Nothing
+        return None
     else:
-        return Some(result)
+        return result

pyproject.toml

@@ -7,7 +7,6 @@ license = "MIT"
 
 [tool.poetry.dependencies]
 python = "^3.9"
-returns = "^0.18.0"
 
 [tool.poetry.dev-dependencies]
 black = "^21.12b0"