parameters

Parameter qualifiers have the following meaning:

val

The default: Pass by name or value, may be inlined (lazy evaluation), and maybe not.

var

Pass by value, assign to local variable (eager evaluation, copying).

ref

Enforced Lazy evaluation. Pass a pointer to the specified type by value. Automatically dereferenced in function body. Caller will usually explicitly take address, eg &x.

fun

Enforced Lazy evaluation. Pass a closure of a function of unit argument returning the specified value. Automatically called in function body. Caller will usually explicitly wrap, eg { 42 }.