int hMissileControl;
int iReturnCode = launchMissiles(&hMissileControl);
if (iReturnCode == ACCIDENTALLY_HIT_INNOCENTS)
    printf("My bad.");
else
    controlMissile(hMissileControl);

You also have the more common throw/raise paradigm:

MissileController missileController;
try {
    missileController = launchMissiles();
    controlMissile(missileController);
} catch (AccidentallyHitInnocentsException)
    printf("My bad.");

This is the predominant paradigm in popular languages like C++, Java, Python, and Ruby.

I’ve heard complaints from both sides. The C-stylers posit, “throwing exceptions introduces all sorts of hidden, complex return paths in your program!” They’re right. With exceptions, a simple program like the following cannot be guaranteed to be simple. There is much more than meets the eye.

void main() {
    doSomethingSimple();  // this might throw
}

Who knows what doSomethingSimple might throw? When does it throw? Can you guarantee it won’t throw with certain inputs?

Furthermore, there’s the classic edition of the hated “blind man’s catch”:

try
    somethingComplicated();
catch (...)
    printf("Something horrible happened...no idea what.");

Polymorphic exception handling opens the door to horrendous laziness like the sample above. Programmers can simply wrap code in a huge sarcophagus-sized band-aid and hope everything turns out alright. Of course, programmers ought to only catch the exceptions they know they can handle, but instead of doing all that research, they figure catching all exceptions under heaven will suffice.

But the C-style method comes with its own catch (pun intended). Exception throwers rightly argue that error codes have a potentially worse side-effect: code is innocent until proven guilty. Now, in our democracy, “innocent until proven guilty” is a jolly good thing to have. But in programming languages, it’s nigh deadly. What I mean is this: in a C-style program, you ignore errors by doing nothing at all. If you want to know an error happened, you have to explicitly check your return codes. But in a throw-style program, the only way to ignore an error is to explicitly catch it. Blindly ignoring errors is a deadly thing to do in programming, and that’s what C-style programming gives you by default.

Take these two programs for example:

// C-style
initializeStuff();  // this returns an error code if it fails
doTheRest();

// throw-style
initializeStuff();  // this throws if it fails
doTheRest();

Do you see the difference? The code is identical. But one of these programs will blindly doTheRest even if the initialization failed. Then when doTheRest explodes miserably, the programmer has to weed through debug logs (if they’re lucky) or use a debugger (if they’re luckier) to find out what happened. But the other program dies instantly with a clean stack trace describing what happened.

So which is better, C-style or throw-style? I don’t know. There have probably been studies to answer this question, but I haven’t read them.

Fortunately, there’s a third way that has the best of both worlds. It doesn’t introduce all sorts of hidden return paths through your code, but it also doesn’t let you blindly keep chugging along when your engine just blew. Because Haskell does such a elegant job of achieving this third way, I’ll use it as an example.

Let’s use sqrt (square root function) as an example. The sqrt function takes integers as input and returns a floating point number as its result. In Haskell that would look like this:

sqrt :: Int -> Double  -- what do we do on negative ints?

The only problem is that sqrt doesn’t work on negative numbers (unless you handle complex numbers, but let’s pretend you don’t feel like doing that right now). So when sqrt is handed a negative number, what do you do? The C-stylers would say that you need to return an error code (and unkindly force the output to a pointer-ridden input argument). The throwers would say to throw. But this third way does neither. Look at the new type signature:

sqrt :: Int -> Maybe Double  -- I might work, I might not, depending on what you give me.

This new type signature means that sqrt might return a Double-floating point number, or it might return Nothing.

Instead of throwing, Haskell’s type system lets you wrap your return value in a thing called a Maybe. This Maybe thing basically tells the compiler that the value will either be a Double or Nothing.

Now, if you are doing normal things with your sqrt function, everything will work jolly well. But if you accidentally give it -453, it will return Nothing and everything will halt. Of course, like the throwing paradigm, you can, if you want, handle this Nothing case and keep on moving. But, by default, your program will not ignore the problem.

This gives you the best of both worlds. Your functions only have one return path, but your program can’t blindly keep trucking if something goes horribly wrong.

Haskell has other types like Maybe that allow functions to return more than just Nothing, perhaps an error description or an error code.

Haskell’s common method of error handling isn’t confined to just Haskell, though. With a little OOP magic, it’s easy to make functions in C++ that have similar behavior. But Haskell’s system is especially good at it, which is why it’s so common.

Maybe the next time you want to handle errors, you’ll consider Maybe.

The Bible is very clear about what it means when it says “walk by the Spirit,” but I have found that the truth is so foreign to my earthly nature that personally grasping its meaning has been extremely difficult. It is like trying to describe color to a man born blind or attempting to draw sound on paper. The truth of walking with the Spirit is so foundational and basic our worldly-wise minds struggle to know its simplicity. Yet its meaning is as plain as day: if you would experience the glory and love of the Spirit of God by your side at every moment, if would have eternal peace in chaos, love in the midst of hate, joy while suffering, abundant life as you die, do only this: believe (and believe always) that you are raised with Jesus Christ through his atonement and victory. Doing this is not an attempt to convince yourself of some distant, intangible reality. Doing this is humbly submitting to the literal reality of the gospel: free grace to all.

But even the smallest task is impossible to a dead man! So, being a raised dead man myself, I find that this small task is very difficult. I strive to walk in this way by studying the Word of God that my mind will be transformed and believe accurate thoughts instead of lies. I have found also that by continuously offering up praise in my heart, my soul is warmed by God’s presence and strengthened by his might. I strive to pray and repent often so my heart remains soft and loving. And I strive to think regularly on God’s grace and glory. By these I find that the fruit of the Spirit are poured into my soul giving me the power to love and do what pleases God. Most of all, they bring me to the worship and enjoyment of the Most High God and His Son Jesus Christ.

These terms are warnings. Just as the valley of Hinnom was a real and terrible place, so God has prepared a more real and more terrible place to punish the wicked after death. These are the images Jesus intends to evoke when he warns us to “fear him who, after he has killed, has authority to cast into hell” (Luke 12:5).

Unlike many Christians, the fear of Hell did not play a large part in my conversion. But since that gracious day, the gravity of Hell has steadily increased in my mind. In fact, without Hell, the God I have loved would not be loving at all. How could God be just without punishing the crimes that men and women have done against him? How could God be holy without purging his creation, his tabernacle, of the vileness of sin? But most of all, Hell is the reality that Jesus endured on the cross. Oh how horrendous Hell is! But even the tortures of Hell could not keep Jesus from delivering us. Even Hell could not discourage his love. He entered Hell for us, only to exit alive.

— Philippians 4:8 (ESV)

The culmination of all these attributes of Jesus is also the culmination of the believer’s meditation: worship. Jesus wants our meditation to always end in worship. And why shouldn’t it? We have seen more than enough to solicit our praise and attract our hearts. If our meditation does not lead to worship, somewhere along the way we went astray in our musings.

Thus, the last and final place for meditation is on those things that are worthy of praise. And there is really only one who is worthy of praise, only one who has the right to be worshipped. That is God himself.

— Philippians 4:8 (ESV)

Unlike the words Paul has used so far, excellence is not an attribute in itself. Rather, it is a degree of quality. Here Jesus is reminding us not just of his own qualities, but of the high and excellent degree of his qualities.

Jesus is not only true, but the truth. He is the ultimate truth and the source of all truth. He is the light and the life of men. He is not only honorable, but the standard by which all honorable things are measured. He is not only right by happenstance, but he defines rightness and has carefully planned it. He is not only pure, but he is the most excellent pure. He is not only without defect, but infinite and incorruptible. He does not simply possess beauty, but he is beauty and loveliness itself. He creates attraction and passion and romance. No one can choose to commend him at will, but he demands to be commended by his greatness. He is excellent and the most excellent of all.

— Philippians 4:8 (ESV)

The Greek word here for commendable (or good report, or good repute, or admirable in the other translations) only occurs in the New Testament once, here in this verse. It refers to things spoken in a kind spirit and with good-will toward others. It refers to things that should be commended, repeated, imitated, learned, taught, and desired.

Jesus taught us what is commendable when he said that “it is more blessed to give than to receive” (Acts 20:35). The most commendable thing of all is to obey the first and great commandment, “to love the Lord your God” (Matthew 22:37), and secondly, to “love your neighbor as yourself” (Matthew 22:38). In fact, love is the fulfillment of all the law, thus, “a new commandment [Jesus gives] to you, that you love one another: just as [he has] loved you, you also are to love one another” (John 13:34).

We learn what is commendable most vividly when we dwell on what Jesus has done. Since we are commanded again and again throughout scripture to be imitators of Christ, it is vital that we develop a joy and love for who he is and what he’s done. Jesus’ selfless love for us culminated on the cross, where we are commanded to follow.

Have this mind among yourselves, which is yours in Christ Jesus, who, though he was in the form of God, did not count equality with God a thing to be grasped, but emptied himself, by taking the form of a servant.

— Philippians 2:5-7 (ESV)

— Philippians 4:8 (ESV)

Loveliness describes yet another facet of God’s person. But loveliness cannot be separated from truth, honor, rightness, or purity. It is an attribute that can only be possessed by someone who has all the others too.

God wants us to dwell on things that are lovely, things that are pleasing, things that are attractive. The world has many lovely, pleasing, and attractive things to offer us. Does he mean to dwell on these? Certainly not. The loveliness of the world is a dull shadow of the loveliness it once had in God’s presence. Despite the great beauty that surrounds us, God has cursed this world and has sworn to return with judgment and destruction. What we see now is the rotting shell of a once-glorious world and humanity. That original beauty has been shattered by sin. Now the world’s beauty is often deceptive because people worship the creature rather than the Creator and destroy themselves.

But God does want us to pursue and dwell on beauty, except it is a better beauty than the world has to offer. It is the beauty if his own works, his own words, and his own person. Most importantly, God wants us to see the beauty of his Son Jesus. Jesus is the source of all beauty, and nothing can be called lovely without having his fingerprints all over it.

Most lovely of all is the love that Jesus has demonstrated toward his unlovely people. His love to forgive and reconcile and transform is the most lovely thing to behold. Seeing this loveliness has immense transforming power, as 1 John declares:

We know that when he appears we shall be like him, because we shall see him as he is.

— 1 John 3:2 (ESV)

— Philippians 4:8 (ESV)

Pure things are immaculate, chaste, clean, and free from defect or corruption. God is pure, and he cannot be corrupted (1 John 3:3). But man stands in stark contrast to God’s purity. Though made pure and innocent, we have fallen far from our original purity. We are now impure, unclean, full of corruption and spiritually dead (Romans 3, Ephesians 2:1).

Dwelling on pure things means setting our mind on the Spirit and not on the flesh (Romans 8). It means not meditating on our own thoughts, but on the thoughts of God. It means not dwelling on our own ideas, ambitions, and desires but on the ambitions and desires of God. It means putting off the old man and putting on the mind of Christ.

Because we are corrupt and totally depraved in every realm, we do not know purity intrinsically. It must be taught and demonstrated to us. This is done through the Holy Spirit by revealing to us the purity of Jesus. As we meditate on Jesus’ purity and the vast distance between his purity and ours, we will be overwhelmed by his love to span that gap and embrace our impurity. By justification our impurity is covered by Jesus’ purity. By sanctification, the reality of God’s justifying work on the cross shapes our hearts to become increasingly pure.

— Philippians 4:8 (ESV)

Right things (or just things in the KJV) are those that have the approval of God. They comply with his desires and they are in accordance with his commands. Throughout the Bible, we learn that “the precepts of the Lord are right” (Psalm 19:8), that “he leads the humble in what is right” (Psalm 25:9), that “right are [his] rules” (Psalm 119:137), that “the Holy Spirit was right” (Acts 28:25), and that “anyone who fears him and does what is right is acceptable to him” (Acts 10:35).

But the ultimate rightness is found in Jesus Christ. Jesus declared this when he said that “[my Father] has not left me alone, for I always do the things that are pleasing to him” (John 8:29). We are to dwell on and be amazed by how accurate and enlightening God’s word is. We are to recognize and appreciate how helpful and loving are his right ways, his right paths, and right precepts. As we recognize God’s rightness, we will more quickly incline to his instruction and more eagerly come to him for help. And this will produce sanctifying change in our hearts.

— Philippians 4:8 (ESV)

Again, the Lord Jesus wants his people to meditate on things that are honorable, or honest (KJV). These are the things, actions, or people who are deserving of respect. Honorable things don’t appear out of nowhere. They earn their title. They are untarnished and unmarred. They have demonstrated greatness, beauty, and goodness, even through various tests and trials.

James tells us that “every good gift and every perfect gift is from above, coming down from the Father of lights with whom there is no variation or shadow due to change” (James 1:17). And John the Baptist reiterates it when he asserts that “a person cannot receive even one thing unless it is given him from heaven” (John 3:34). And again Jesus himself says that “apart from [him] you can do nothing” (John 15:5). So clearly there is nothing good or perfect that has not come “from above.” Thus, in order to meditate on honorable things, we must meditate on those things that God has given from above.

What things has God given from above? He has given his word, his “message declared by angels” (Hebrews 2:2a). He has given his judgment on this world and its ruler (Hebrews 2:2b, John 16:11). He has given his Holy Spirit to those who believe (John 14:16). He has given his beautiful creation (Psalm 19:1). He has given physical, temporal happiness (Psalm 104:15). But most of all, most important of all, and most honorable of all, he has given us his own Son (John 3:16). And in his Son, he has given us forgiveness of sins, eternal life, infinite love, and eternal glory.

It is implied, therefore, that believers are not to meditate on dishonorable things. Dishonorable things are opposed to the honorable things of God. They are “evil thoughts, murder, adultery, sexual immorality, theft, false witness, [and] slander” (Matthew 15:19). They are “all that is in the world—the desires of the flesh and the desires of the eyes and pride of life” (1 John 2:16). These are “not from the Father but…from the world.”