Is there a Phobos function that converts an unsigned integer to a binary string? I've searched, but couldn't find one - just want to make sure I'm not reinventing the wheel by writing my own.
std.conv.to is the swiss army knife of conversion functions, and it supports converting to and from different bases. So, if you want to convert 13 to its base 2 value as a string - "1101" - then you'd do
auto str = to!string(13, 2);
assert(str == "1101");
and to convert a string containing a base 2 integer to an integer, just do the reverse
auto i = to!int("1101", 2);
assert(i == 13);
std.conv.parse has similar functionality, but it's for parsing a value from the beginning of a string (with the idea of parsing out several whitespace-separated values from the string) rather than converting the entire string at once. It also doesn't work to construct a string from a value, just a value from a string.