put myvar {true}

# The simplest flow control is an if. It takes its first argument and
# calls the environment to decide if it is true or false. If it's true
# the "then" branch is executed, if it's false, the "else" branch runs.
if myvar then
	print {myvar is true (1)\n}
else
	print {myvar is false (1)\n}
end


# it is possible to omit the else branch
if myvar then
	print {myvar is true (2)\n}
end

# the then branch may be empty:
if myvar then else
	print {myvar is false (3)\n}
end

# embedding controls is legal:
put foo {false}
if myvar then
	if foo then
		print {myvar and bar are true (4)\n}
	else
		print {myvar is true, bar is false (4)\n}
	end
end