/** @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;
}
}
