HE vs ML discrepancy: ML fails to infinitely loop. (= (loop) (loop)) and !(loop) outputs [(loop)]

[zariuq]

• In HE, the following loops indefinitely (as described in the tutorial).
• In ML, only one step of evaluation is done.

metta+>(= (loop) (loop))
metta+>!(loop)
[(loop)]

metta+>!(if False Success (loop))
[(loop)]

;; From the tutorial, this my-if function should only terminate if the type information is given because "Atom" seems to imply that the variable should't be evaluated unless needed?
;; But this bug in ML breaks it.

;;(: my-if (-> Bool Atom Atom Atom))
metta+>(= (my-if True $then $else) $then)
metta+>(= (my-if False $then $else) $else)
metta+>(= (loop) (loop))
metta+>(= (OK) OK!)
metta+>! (my-if (> 0 1) (loop) (OK))
[OK!]