/** @see jaskell.compiler.JaskellVisitor#visit(Application) */
public Object visit(Application a) {
try {
/* get type of function */
Expression fun = a.getFunction();
/* get type deduced from arguments */
LinkedList l = new LinkedList();
Iterator it = a.getArgs().iterator();
while (it.hasNext()) {
Expression e = (Expression) it.next();
l.add((Type) e.visit(this));
}
Type vt = TypeFactory.freshBinding();
Type ft = Types.fun(l, vt);
log.finer("TypeChecker => In application " + a + ", type is " + ft);
/* apply substitution on both types */
ft = subst.substitute(ft);
/* try to unify function type and constructed types */
Type t = (Type) fun.visit(this);
log.finer("In application, function " + fun + " :: " + t);
t = subst.substitute(t);
log.finer("In application, trying to unify function type " + t + " with body " + ft);
/*
* TODO : problem with unification of constrained types
*/
TypeApplication uni = (TypeApplication) tu.unify(t, ft, typeVariablesMap);
/* sets type of functional expression - this allows
* polymorphic functions to receive several types
* in the same code */
// fun.setType(uni);
/* apply arguments type to compute return type */
log.finer("Done unify application :" + uni);
it = PrimitiveType.functionIterator(uni);
Iterator it2 = l.iterator();
TypeApplication ut = uni;
while (it2.hasNext()) {
/* type of argument */
Type at = (Type) it2.next();
ut = (TypeApplication) it.next();
/* try unification */
tu.unify(((TypeApplication) ut.getDomain()).getRange(), at, new HashMap(typeVariablesMap));
}
ft = subst.substitute(ft);
fun.setType(ft);
log.finer("Setting type of functional element [" + fun + "] to :" + ft);
a.setType(ut.getRange());
return ut.getRange();
} catch (TypeError te) {
if (te.getLineCol() == null) te.setLineCol(a.getTag("source"));
throw te;
}
}
/**
* Returns null or throws a TypeError if type cannot be inferred for any definition found.
* Verifies that main symbol in Main module is typed as <code>IO ()</code>.
*
* @see jaskell.compiler.JaskellVisitor#visit(Module)
*/
public Object visit(Namespace a) {
// visit definitions
Iterator it = a.getAllBindings().entrySet().iterator();
while (it.hasNext()) {
Map.Entry entry = (Map.Entry) it.next();
String name = (String) entry.getKey();
Expression def = (Expression) entry.getValue();
Type type = (Type) def.visit(this);
def.setType(type);
log.finer("TypeChecker => END Visiting " + name);
}
log.finer("Substitution map = " + typeVariablesMap);
return null;
}
/** @see jaskell.compiler.JaskellVisitor#visit(Let) */
public Object visit(Let a) {
Type ret = a.getType();
if (ret != null) return ret;
// visit definitions
Iterator it = a.getBindings().entrySet().iterator();
while (it.hasNext()) {
Map.Entry entry = (Map.Entry) it.next();
String name = (String) entry.getKey();
Expression def = (Expression) entry.getValue();
log.finer("Visiting " + name);
def.setType((Type) def.visit(this));
}
// visit body
ret = (Type) a.getBody().visit(this);
a.setType(ret);
// return type of body
return ret;
}
