advanced lang's do type inferencing

10.8: web.adda/{ml, haskell}/advanced type systems?:

Operations on algebraic data types can be defined by using pattern matching

[this is, at least in their example,

the same as being able to program using the same code math does:

Tree.type = { variant? (Empty: null, Leaf: Int, Node: (l.Tree, r.Tree) };

depth(x.tree).int`=

{ return x`variant ?

(empty: 0

, leaf: 1

, others: 1 +max(depth x`left, depth x`right)

)} .

. this is a somewhat higher level than would be done in ada,

where you'd have to spell out

how you would be determining what variant a subtree was,

eg: empty(x.tree).truth`= '(return x=nil)

] .