Match With Variables

In the Match Statement lesson every pattern was a literal value, like 1: or "bow":. A pattern can also be a constant or a variable: match compares the value with what that name holds when the line runs:

const SECRET := 42
var guess := 42
match guess:
	SECRET:
		print("You found it!")
	_:
		print("Try again")

You found it!

The second new pattern is the binding pattern: var followed by a new name. Like _, it matches any value, and it also stores that value in the new variable, which you can use inside its block:

var level := 5
match level:
	1:
		print("Tutorial")
	var n:
		print("Level %d is locked" % n)

Level 5 is locked

A binding pattern is most useful when you match the result of an expression, which has no name of its own:

var roll_a := 4
var roll_b := 6
match roll_a + roll_b:
	12:
		print("Double six!")
	var total:
		print("You rolled ", total)

You rolled 10

A binding pattern matches everything, so it goes last, like _. Its name must be new: var level: in the second example would be an error, because level already exists. It also cannot share a line with other patterns separated by commas.

match compares types strictly: the string "5" does not match the pattern 5, and neither does the float 5.0. Convert text read from input with int() before you match it against numbers.