===============================
If expression
===============================

if grep found file {
  echo present
} else {
  echo absent
}

---

(source_file
  (if
    (command
      (command_name
        (identifier))
      (word)
      (word))
    (block
      (command
        (command_name
          (identifier))
        (word)))
    (block
      (command
        (command_name
          (identifier))
        (word)))))

===============================
While statement
===============================

val i = 0
while $i < 10 {
  i += 1
}

---

(source_file
  (variable_declaration
    (identifier)
    (primary
      (number)))
  (while
    (infix_expression
      (expansion
        (variable
          (identifier)))
      (primary
        (number)))
    (block
      (assignation
        (identifier)
        (primary
          (number))))))

===============================
Function declaration
===============================

fun square(n: Int) -> Int = $n * $n

---

(source_file
  (function_declaration
    (identifier)
    (parameter_list
      (function_parameter
        (identifier)
        (type_identifier
          (identifier))))
    (type_identifier
      (identifier))
    (infix_expression
      (expansion
        (variable
          (identifier)))
      (expansion
        (variable
          (identifier))))))

===============================
Implicit return
===============================

fun fibonacci(n: Int) -> Int =
  if $n <= 1 {
    1
  } else {
    fibonacci($n - 1) + fibonacci($n - 2)
  }

---

(source_file
  (function_declaration
    (identifier)
    (parameter_list
      (function_parameter
        (identifier)
        (type_identifier
          (identifier))))
    (type_identifier
      (identifier))
    (if
      (infix_expression
        (expansion
          (variable
            (identifier)))
        (primary
          (number)))
      (block
        (primary
          (number)))
      (block
        (infix_expression
          (call_expression
            (identifier)
            (argument_list
              (infix_expression
                (expansion
                  (variable
                    (identifier)))
                (primary
                  (number)))))
          (call_expression
            (identifier)
            (argument_list
              (infix_expression
                (expansion
                  (variable
                    (identifier)))
                (primary
                  (number))))))))))