public static Symbol Intern(string name)
{
Symbol value;
if (InternedSymbols.TryGetValue(name, out value)) {
return value;
}
value = new Symbol(name);
InternedSymbols[name] = value;
return value;
}
public TaggedType(Symbol tag, object data)
{
_tag = tag;
Data = data;
}
public SymbolNotFoundException(Symbol s)
: base(string.Format("Symbol {0} is not defined.", s.Name))
{
}
public object ToplevelLookup(Symbol name)
{
object value;
if (!_toplevelEnv.TryGetValue(name, out value)) {
throw new SymbolNotFoundException(name);
}
return value;
}
public bool ToplevelIsDefined(Symbol name)
{
return _toplevelEnv.ContainsKey(name);
}
public void ToplevelDefine(Symbol name, object value)
{
_toplevelEnv[name] = value;
}