/** @see jaskell.compiler.JaskellVisitor#visit(ConstructorPattern) */
public Object visit(ConstructorPattern a) {
String cname = a.getConstructor().getName();
/* retrieve parameter types of constructor */
ConstructorDefinition ctor = (ConstructorDefinition) a.getConstructor().lookup(cname);
if (ctor == null) throw new TypeError("Undefined constructor pattern " + a);
/* type of data constructed by constructor */
TypeInstantiator ti = new TypeInstantiator(ctor.getDataType());
Type rtype = ti.instance();
Map map = ti.getMap();
TypeSubstitution ts = new TypeSubstitution(map);
Iterator ittypes = ctor.getParameters().iterator();
/* retrieve type of patterns */
Iterator it = a.getSubPatterns();
while (it.hasNext()) {
try {
Pattern p = (Pattern) it.next();
Type actual = TypeFactory.freshBinding();
Type formal = ts.substitute((Type) ittypes.next());
/* unify both types */
p.setType(tu.unify(formal, actual, typeVariablesMap));
} catch (NoSuchElementException nex) {
throw new TypeError("Wrong number of arguments to pattern " + a);
}
}
a.setType(rtype);
return a.getType();
}
/** @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;
}
}
/** @see jaskell.compiler.JaskellVisitor#visit(Abstraction) */
public Object visit(Abstraction a) {
try {
Type t = a.getType();
if (t != null) return subst.substitute(t);
log.finest("Visiting abstraction : " + a);
Expression body = a.getBody();
/* duplicate bindings map to assign types to variables */
pushContext(a.getBindings());
/* create fresh type variables as type for each bound
* variable */
Iterator it = namesMap.values().iterator();
LinkedList tl = new LinkedList();
while (it.hasNext()) {
LocalBinding name = (LocalBinding) it.next();
Type vt = TypeFactory.freshBinding();
name.setType(vt);
tl.add(vt);
}
Type tv = TypeFactory.freshBinding();
/* create type with all variables for function */
Type ft = Types.fun(tl, tv);
log.finer("In abstraction, setting type to " + ft);
a.setType(ft);
/* analyze body */
Type bt = (Type) body.visit(this);
/* unify return type of function with type of body */
Type ret = tu.unify(PrimitiveType.getReturnType(ft), bt, typeVariablesMap);
TyvarSubstitution tys = new TyvarSubstitution(typeVariablesMap);
tys.visit(a);
log.finer("Done abstraction, setting type from " + ft + " to " + a.getType());
popContext();
return a.getType();
} catch (TypeError te) {
if (te.getLineCol() == null) te.setLineCol(a.getTag("source"));
throw te;
}
}