Qualification principle


In programming language theory, the qualification principle states that any semantically meaningful syntactic class may admit local definitions. In other words, it's possible to include a block in any syntactic class, provided that the phrases of that class specify some kind of computation.
A common examples for of this principle includes:

if


let
val g = 9.8
in
m * g * h
end


local
fun multiple =

in
fun leap =

andalso not multiple )
orelse multiple
end