Learning python specific syntax after using other scripting languages for years

[mpd]

why does it not convert things to be printable without converting types?

Unlike a lot of languages, Python doesn't let you add numbers to strings and vice versa. The following is simply not supported:

s = "Hello " + 5

I can't give you the Pythonic answer for this(i.e., why the designers chose not to support it). Personally, I don't like implicit casting and from my own experience, using a wide range of languages, I prefer it this way.

Instead Python supports string formatting.
https://docs.python.org/2/library/string.html
https://docs.python.org/2/library/functions.html#print

So here's your code:

print(str(k) + ":" + str(v) + "\n")

Which is creating a string by concatenating the various pieces and if 'k' or 'v' are integers, it won't work.

It can be done in two ways:

print("%s:%s"%(k, v))
print("{0}:{1}".format(k,v))

Personally, I find the latter easier to read. Note that I didn't include the '\n', that's included automatically, unless you specify something different with the end keyword argument.

You can also simply print integers without effort:

x = 5
print(x)