bahaghari/lib: add radian <-> degree conversion in math subset

subprojects/bahaghari/lib/default.nix

@@ -50,5 +50,5 @@ pkgs.lib.makeExtensible
 
     inherit (self.hex) isHexString;
     inherit (self.math) abs pow percentage factorial floor ceil round round'
-      summate product sqrt;
+      summate product sqrt remainder mod radiansToDegrees degreesToRadians;
   })

subprojects/bahaghari/lib/math.nix

@@ -313,4 +313,35 @@ rec {
        => 24
   */
   product = builtins.foldl' builtins.mul 1;
+
+  /* Given a number in radians, convert it to degrees.
+
+     Type: radiansToDegrees :: Number -> Number
+
+     Example:
+       radiansToDegrees bahaghariLib.math.constants.pi
+       => 180
+
+       radiansToDegrees 180
+       => 10313.240312355
+  */
+  radiansToDegrees = x:
+    x * 180.0 / constants.pi;
+
+  /* Given a number in degrees unit, convert it to radians.
+
+     Type: degreesToRadians :: Number -> Number
+
+     Example:
+       degreesToRadians 180
+       => 3.141592653589793238462643383279502884197
+
+       degreesToRadians 360
+       => 6.283185307
+
+       degreesToRadians 95
+       => 1.658062789
+  */
+  degreesToRadians = x:
+    x * constants.pi / 180.0;
 }

subprojects/bahaghari/tests/lib/math.nix

@@ -332,4 +332,34 @@ lib.runTests {
     expr = round' (self.math.exp 2);
     expected = 7.3890560989;
   };
+
+  testDegreesToRadians = {
+    expr = self.math.degreesToRadians 180;
+    expected = self.math.constants.pi;
+  };
+
+  testDegreesToRadians2 = {
+    expr = self.math.degreesToRadians 360;
+    expected = self.math.constants.pi * 2;
+  };
+
+  testDegreesToRadians3 = {
+    expr = self.math.round' (-5) (self.math.degreesToRadians 95);
+    expected = 1.65806;
+  };
+
+  testRadiansToDegrees = {
+    expr = self.math.radiansToDegrees self.math.constants.pi;
+    expected = 180;
+  };
+
+  testRadiansToDegrees2 = {
+    expr = self.math.round' (-3) (self.math.radiansToDegrees 180);
+    expected = 10313.24;
+  };
+
+  testRadiansToDegrees3 = {
+    expr = self.math.round' (-3) (self.math.radiansToDegrees 4.5);
+    expected = 257.831;
+  };
 }