             "sin":      sin,
             "tan":      tan,
             // Angular conversion
-            //            "degrees": degrees,
-            //            "radians": radians,
+            // "degrees": degrees, // TODO
+            // "radians": radians, // TODO
             // Hyperbolic functions
             "acosh":    acosh,
             "asinh":    asinh,

            "ceil":     ceil,
            "copysign": copysign,
            "fabs":     fabs,
            //            "factorial": factorial,
            "floor":    floor,
            "fmod":     fmod,
            "frexp":    frexp,
            //            "fsum": fsum,
            "isinf":    isinf,
            "isnan":    isnan,
            "ldexp":    ldexp,

            "=":        { $0 = $1 },
            // Misc.
            "abs": abs,
            // "append": op.add, // TODO
            // "apply": apply, // TODO
            "begin":    { $0[-1] },
            "car":      { $0[0] },
            "cdr":      { $0.dropFirst() },
