Constant

A constant is a global value that cannot be changed. The following snippet defines a global constant named price typed tez equal to 10 tez:

constant price : tez = 10tz

The following defines a string typed constant named msg :

constant msg : string = "Hello world"

Note that constant values are not transcoded to contract storage: they may be seen as convenient aliases when writing contract's code.

Variable

A variable is a global value that can be changed. The following snippet defines 2 global variables named seller and buyer typed role equal to a (here random) addresses:

variable seller : role = @tz1KksC8RvjUWAbXYJuNrUbontHGor25Cztk
variable buyer  : role = @tz1KUbontHGor25CztkksC8RvjUWAbXYJuNr

​