Mixed-type rules

There's no general implicit conversion. Each operator has a short list of kind combinations it understands. Any other combination doesn't raise an error. It quietly gives Integer 0 (or false for an ordering) and the script keeps running. That's deliberate, so one odd value doesn't abort an action halfway through. It also means a mistyped expression fails silently, so check with UtilityPrint when a result looks wrong.

Operator	Accepted combinations → result	Anything else
+	Text + Text → Text (concatenation) Integer + Integer → Integer Integer/Real mix → Real	0
- *	Integer ∘ Integer → Integer Integer/Real mix → Real	0
/	Integer / Integer → Integer, truncated toward zero (-7 / 2 is -3) Integer/Real mix → Real dividing by zero → 0 or 0.0, no error	0
== !=	same kind → compared by value (Text exactly and case-sensitively, Window by handle) Integer vs Real → compared numerically (5 == 5.0)	never equal: 1 == true, "5" == 5 and w == 0 are all false
< <= > >=	two numbers (Integer/Real mix allowed) → numeric order Text vs Text → ordinal, case-sensitive (UTF-16 code units: "Z" < "a")	false for all four, so !(a < b) doesn't mean a >= b here
&& || !	any kinds, via truthiness → Bool
& | ^	Integer ∘ Integer → Integer	0 (a Bool or Real operand counts: true & true is 0)
<< >>	Integer by Integer 0–63 → Integer. >> keeps the sign: -16 >> 2 is -4.	0, including shift amounts below 0 or above 63
unary -	Integer → Integer, Real → Real	0
~	Integer → Integer (~0 is -1)	0

Converting between kinds:

From → To	How
Integer → Real	automatic when passed to a builtin parameter declared Real; elsewhere n * 1.0 (any arithmetic with a Real gives a Real)
Real → Integer	MathRound(r) (halves away from zero), MathFloor(r) or MathCeil(r)
anything → Text	StringFormat("{0}", value, "")
Bool → Integer	if (b) n = 1; else n = 0;
Text → number	StringToNumber(text, false) for what a person typed (their regional format; digit groups must follow it, so 1,5 isn't a number for an English (United States) user), true for machine text (. decimal point, no grouping). Integer when whole, else Real; StringIsNumber first if the text might not be a number (see this example).
number → Text	StringFromNumber(n, decimals, invariantCulture), decimals -1 for as many as needed
Integer → hex Text	no builtin does this. Build it with shifts (see this example).