Lists, functions and control flow

Documentation status: guide — see Maturity and evidence.

functionalP includes list-oriented expressions, ranges, conditions, loops, named functions, and advanced functional forms.

Lists and ranges

(1, 2, 3);
();
(1, 2, (5, 4, 6));
1 .. 5;

Useful list operators include head, tail, last, length, reverse, drop, and take.

tail (1, 2, 3);
length (1, 2, 3, 4);
reverse (1, 2, 3);

status := 0;
if (status = 0) then
begin
  Result := 'ready';
end
else
begin
  Result := 'blocked';
end;

sum := 0;
for value in (1, 2, 3, 4) do
begin
  sum := sum + value;
end;
Result := sum;

Loops should remain small. Cross-object or long-running coordination belongs in a process model.

function double(value)
begin
  value * 2;
end;

Result := double(4);

A function can be used with functional operators:

Result := map double (1 .. 5);

These are advanced features. Use them for local transformations, not to hide durable business rules.

Result := (lambda(x) x * x) 4;

function normalize(value)
begin
  case value of
    () :- ()
  | _  :- value
  end;
end;