public Type eval() {
if (reduced != null) return reduced;
if (inEval) return this;
final Type baseEval = base.deref().eval();
final Type argEval = arg.deref().eval();
if (!(baseEval instanceof TypeCons))
// error has been raised
return this;
final TypeCons cons = (TypeCons) baseEval;
final Type body = cons.getBody();
if (body == null) return reduced(baseEval, argEval);
// check base abs param kind against arg kind
if (!checkKindAgreement(cons, argEval))
// error has been raised
return this;
// evaluate by building param->arg subst map and
// applying it to body term
final SubstMap argMap = new SubstMap();
final Collection<TypeParam> params = body.getParams().values();
if (params.size() == 1) {
final TypeParam param = params.iterator().next();
assert param.getTypeScope() == body : "nope";
argMap.put(param, argEval);
} else {
if (!(argEval instanceof TypeTuple)) assert false;
final Iterator<Type> argList = ((TypeTuple) argEval).getMembers().iterator();
for (final TypeParam param : params) {
assert param.getTypeScope() == body : "nope";
argMap.put(param, argList.next());
}
}
final Type bodySubst = new TypeApplier(body, argMap).apply();
// evaluate body with args substituted for params
inEval = true;
reduced = bodySubst.eval();
inEval = false;
if (Session.isDebug())
Session.debug(
body.getLoc(), "eval {0}({1}) => {2}", body.dump(), argMap.dump(), reduced.dump());
return reduced;
}
public TypeParam(final TypeParam param) {
this(param.getLoc(), param.getName(), param.getKind(), param.getConstraint());
}