Contract data is read and written with actions. They are the entry points of the contract.

Arguments

An action may take input arguments. For example the snippet below declare an action named complete which takes two arguments value and amount , respectively of type string and int:

action complete (value : string, amount : int) {
​
  ...  (* action body *)
​
}

Sections

An Action is made of sections listed below:

For example, the complete action example may be enhanced as follows:

constant owner : role = @tz1KksC8RvjUWAbXYJuNrUbontHGor25Cztk
​
variable threshold : tez = 100tz
​
action complete (value : string, amount : int) {
  called by owner
  
  require {
    r : transferred > threshold
  }
  
  effect {
    ... (* effect code *)
  }
}

In the expression r : ... line 8 above, r is a label for the require expression (see Label section below).

Label

In Archetype, some expressions are named. The following syntax is used to name an expression:

l : ... expression ... /* l is a label */

The following is the list of expressions that require a label:

Effect

Local variable

A local variable is declared as exampled below:

let p = amount + 10tz in
...

Data assignment

A variable (global or local) is assigned a new value as exampled below:

p := amount;

After this instruction, the value of p is the value of amount.

Currency transfer

The instruction to transfer currency is exampled below:

transfer 10tz to owner

Conditional

The basic conditional expression is exampled below :

if transferred > threshold then
  transfer price
else
  fail "not enough"

The require expression fails if the condition is not met:

require (transferred > threshold)

The failif expression fails if the condition is met:

failif (transferred <= threshold)

Asset collection

Consider the following car asset identified by its vin id:

asset car identified by vin {
  vin : string;
  model : string;
  year : int;
}

The following table gives the basic instructions to get, add, remove, update an asset.

Advanced operations over a collection are listed in the table below:

Iteration over a collection is as follows:

for c in car do
  ...
done

​