Customer behavior type variable
is mainly used for getting the information of customers' basic attributes.
Type elaboration can be performed by solving a system of equalities and inequalities between types and type variables
generated from the subexpressions of a given program, as specified in Figure 9.
In terms of the polymorphic target language, we regard type variables
as ranging over various "store shapes" or state types, so that in a type [Alpha] ??
* "% of stores" type variables
in multiplicative (semilog) models (as opposed to 0/1 variables which imply the model is using homogeneous observations)
(Note that [H] is impossible because [K] is not a nested embedding and b [right arrow], fh is not a type variable
.) If both are [F], then the induction hypothesis and one use of [F] let us conclude [Psi](e').
let [Alpha] [not element of] V be a fresh type variable
Note that we do not allow the type variable
binders [[bar]X] to be inferred.
If a polymorphic type variable
[Alpha] has the 32-bit kind, then objects of type [Alpha] can be passed in general-purpose registers, and tuple offsets may be computable for fields appearing after a field of type [Alpha].
Polmorphic types of the form [inverted]A[Alpha] [is less than]: [Rho].[Sigma] constrain instantiations of a type variable
[Alpha] to the set of types described by [Rho].
We can also use <x>, [([Lambda]x.e)e'], [[Lambda]x.e], [e], [e'] as type variables
, and for a type system such as simple types where there is no nontrivial subtyping between function types, we get, among others, the following constraints on type correctness:
In comparison, Johnson and Walz's unification algorithm [Johnson and Walz 1986] reports that the "false" expression must have the type int, because it selects the most "popular" types if multiple, conflicting types are bound to a type variable
[Sigma.sub.n], also written [k.sup.f??]) followed by either a single type variable
([Alpha]) or the empty type ([Phi]):