/** @see jaskell.compiler.JaskellVisitor#visit(QualifiedVariable) */
public Object visit(QualifiedVariable a) {
Module mod = null;
Iterator it = a.getPath().iterator();
while (it.hasNext()) {
String mname = (String) it.next();
if (mod != null) mod = (Module) mod.lookup(mname);
else mod = (Module) Module.getToplevels().get(mname);
}
/* module found */
if (mod != null) {
Expression def = mod.lookup(a.getName());
if (def == null) throw new CompilerException("Unknown variable " + a.getName());
Type t = def.getType();
if (t == null) t = (Type) def.visit(this);
/* as it is the case for variable, we assume
* that a defined symbol may be overloaded (only for primitive types)
* so we return a type variable and defers choice of
* symbol to a later stage
*/
a.setType(t);
return t;
}
throw new CompilerException("Unable to find module needed for variable " + a.getName());
}
/** @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();
}
/**
* 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;
}
/** @see jaskell.compiler.JaskellVisitor#visit(Alternative) */
public Object visit(Alternative a) {
try {
Type tex = (Type) a.getExpression().visit(this);
log.finer("In alternative, type of expression " + a.getExpression() + " is " + tex);
/* set type of bound variable */
LocalBinding lb = a.getBinding();
if (lb != null) lb.setType(tex);
/* visit type of alternatives */
Iterator it = a.getChoices();
Type ptype = tex;
Type btype = null;
while (it.hasNext()) {
Map.Entry entry = (Map.Entry) it.next();
/* checkt type of pattern */
Type pt = (Type) ((Pattern) entry.getKey()).visit(this);
if (ptype == null) ptype = pt;
else ptype = tu.unify(pt, ptype, typeVariablesMap);
log.finer("In alternative, unifying pattern type " + pt + " to " + ptype);
Expression expr = (Expression) entry.getValue();
/* check type of body */
Type bt = (Type) expr.visit(this);
// /* apply substitution with type variables from pattern */
// TypeSubstitution ts = new TypeSubstitution(typeVariablesMap);
// expr.visit(ts);
if (btype == null) btype = bt;
else btype = tu.unify(bt, btype, typeVariablesMap);
log.finer("In alternative, unifying body type " + bt + " to " + btype);
}
/* visit default choice */
Type deft = (Type) a.getWildcard().visit(this);
a.setType(btype);
return btype;
} 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;
}
}
/** @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;
}
}