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Assignment

a := b

Local variable

Assigns value of expression b to variable a. Type of b must be the same as (or compliant with) the type of a.

All types are assignable, except ticket

For example:

var s = "a string";
s := "another string"

Tuple

Assigns a dimension of a tuple variable.

For example:

var t = (2, "a string");
t[0] := 4;
t[1] := "another string";
/* t is (4, "another string") */

Record

Assigns a field value of a record variable.

For example, consider the following record declaration:

record color {
red : bytes;
green : bytes;
blue : bytes
}

Then the following assigns the red field:

var r = { red = 0xc6; green = 0x6d; blue = 0x32 };
r.red := 0xc8;
/* r is { red = 0xc8; green = 0x6d; blue = 0x32 } */
info

Other assignment operators below are also available for tuple dimension and record field.

a ?:= b : e

Assigns the some value of option b argument to a, and fails with e otherwise.

For example:

var a : 0;
a ?:= unpack<nat>(0x0505) : "ERROR"

This is equivalent to:

var a = 0;
match unpack<nat>(0x0505) with
| some(v) -> a := v
| none -> fail("ERROR")
end

a += b

Increments variable a (local variable, tuple dimension or record field) by value of b. It is equivalent to a := a + b (see + operator).

Fails with

does not fail

a -= b

Decrements variable a (local variable, tuple dimension or record field) by value of b. It is similar to a := a - b (see - operator). It is not exaclty equivalent because if may fail on nat values (see fail conditions below).

Fails with

"NAT_NEG_ASSIGN"

when a (typed nat)is less than b (typed nat).


"INVALID_NEGATIVE_TEZ"

when a - b value typed tez is negative.

a *= b

Multiplies variable a (local variable, tuple dimension or record field) by value of b. It is equivalent to a := a * b (see * operator).

Fails with

does not fail

a /= b

Divides variable a (local variable, tuple dimension or record field) by value of b. It is equivalent to a := a / b (see * operator).

Type of a

Type of b

WITH TYPE PROMOTION

Fails with

does not fail

a &= b

Assigns a and b to variable a (local variable, tuple dimension or record field) (see and operator).

Type of a

Type of b

Fails with

does not fail

a |= b

Assigns a and b to variable a (local variable, tuple dimension or record field) (see or operator).

Type of a

Type of b

Fails with

does not fail