ASTTypeDef.java

import java.util.HashMap;
import java.util.HashSet;
import java.util.Set;

public class ASTTypeDef implements ASTNode {
    HashMap<String,ASTType> ltd;
    ASTNode body;

    public ASTTypeDef(HashMap<String,ASTType>  ltdp, ASTNode b) {
        ltd = ltdp;
        body = b;
    }

    @Override
    public IValue eval(Environment<IValue> env) throws InterpreterError {
        return body.eval(env);
    }

    @Override
    public ASTType typecheck(Environment<ASTType> e) throws TypeCheckError, InterpreterError {
        e = e.beginScope();
        for (String id : ltd.keySet()) {
            e.assoc(id, ltd.get(id));
        }
        ASTType returnType = body.typecheck(e);
        e.endScope();
        return returnType;
    }

    static public ASTType unfold(ASTType t, Environment<ASTType> e) throws InterpreterError {
        Set<String> seen = new HashSet<>();
        while (t instanceof ASTTId tid) {
            if (seen.contains(tid.toStr())) return t;
            seen.add(tid.toStr());
            t = e.find(tid.toStr());
        }
        return t;
    }

}