The point is, we can do arithmetic, but it is ugly. The python now, and a couple of examples (fact and fib) in the next post. Not super happy with this code, but it does the job, and it was from way back when I was still in the early stages of learning python.

# the arithmetic function # eg: arithmetic(|number: 3>,|symbol: +>,|number: 8>) # def arithmetic(x,operator,y): x_label = x if type(x) == str else x.the_label() op_label = operator if type(operator) == str else operator.the_label() y_label = y if type(y) == str else y.the_label() cat1, v1 = extract_category_value(x_label) name, op = extract_category_value(op_label) cat2, v2 = extract_category_value(y_label) if cat1 != cat2 or op not in ['+','-','*','/','%','^']: return ket("") try: x = int(v1) y = int(v2) except ValueError: try: x = float(v1) y = float(v2) except ValueError: return ket("") label = "" if len(cat1) > 0: label = cat1 + ": " if op == '+': return ket(label + str(x + y)) elif op == '-': return ket(label + str(x - y)) elif op == '*': return ket(label + str(x * y)) elif op == '/': if y == 0: # prevent div by zero return ket("",0) return ket(label + str(x / y)) elif op == '%': return ket(label + str(x % y)) elif op == '^': return ket(label + str(x ** y)) else: return ket("") # presumably this should never be reached.I guess a couple of things to note:

1) the |> wrapping around everything is a tad ugly in this case. But we must stick to every object being either a ket or a superposition, otherwise we break our model.

2) heh, the "amplification factor" of this function versus the python "answer = a*b" is huge!

And I guess that is it. I'll put it to use in the next post.

Update: note that the arithmetic function returns |> if the categories/data-types do not match. This is to prevent errors where you mix data-types. eg, say adding pounds and kilos.

Update: the standard solution to arithmetic on kets you are not 100% sure of the data-type is something like this:

arithmetic(to-km |x>,|+>,to-km |y>)which gives an answer in km, assuming |x> and |y> support the to-km operator, independent of the actual type of x and y.

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updated: 19/12/2016

by Garry Morrison

email: garry -at- semantic-db.org