Sequence

The effect of an entrypoint is composed of zero, one or several instructions presented below.

The literal for zero instruction is (); several instructions are separated with ;.

For example, exec entry point does nothing:

entry exec() {
  ()
}

Entry exec below executes instructions instr1 and instr2; note there is no ; after instr2:

entry exec() {
  instr1;
  instr2   /* no ';' after last instruction */
}

In conditional branches of instructions like if then, it is necessary to delimit a sequence of instructions with begin ... end.

For example, instr2 below is always executed because it does not belong to the conditional branch of the if instruction:

entry exec() {
  if expr0 then   /* first instruction  */
    instr1;
    instr2        /* second instruction */
}

In order to execute instr1 and intr2 when epxression expr0 is true, use begin ... end:

entry exec() {
  if expr0 then begin
    instr1;
    instr2
  end
}

Michelson

It is possible to provide a sequence of Michelson instructions with the michelson instruction. For example the following fails if the argument i is positive:

archetype michelson_instruction

entry exec (i : nat) {
  michelson {
    PUSH nat 0;
    COMPARE;
    NEQ;
    IF { PUSH string "NOT_ZERO"; FAILWITH } { PUSH nat 0 }
  }
}

danger

Michelson code's type is not checked by archetype compiler