Operators and Expressions

An expression is a piece of code that produces a value. 2 + 3 is an expression — its result is 5. In this lesson you'll get to know the operators that build expressions in AHA! Lang.

Arithmetic Operators

Note: the division 7 / 3 produces 2, not 2.33 — because Int only stores whole numbers. You can grab the discarded remainder with %.

print(10 / 4); // 2
print(10 % 4); // 2
print(9 % 2);  // 1 — 9 is odd

Operator Priority (Precedence)

Like in math, multiplication comes before addition:

print(2 + 3 * 4);  // 14 — not 20

let a = (2 + 3) * 4; // 20 — parentheses change the order
print(a);

Use parentheses (...) whenever the order of computation needs to be made clear.

Comparison Operators

Comparisons compare two values:

print(5 == 5); // 1 (true)
print(5 != 5); // 0 (false)
print(5 < 3);  // 0
print(5 >= 5); // 1

AHA! Lang's Quirk: The Result Is Int

This is where AHA! Lang differs from Python. The result of a comparison in AHA! Lang is not a boolean type — instead it's an Int 1 (true) or 0 (false).

As a result, a logic result can be used directly in calculations:

let umur = 20;
let dewasa = umur >= 18; // 1

print(dewasa);      // 1
print(dewasa * 100); // 100 — logic flows into arithmetic!

Logical Operators

&& produces 1 if both sides are true, otherwise 0. || produces 1 if either side is true, otherwise 0.

let nilai = 80;
let hadir = 1;

// pass if nilai >= 70 AND present
let lulus = nilai >= 70 && hadir == 1;

print(lulus); // 1

Prefix Operators

There are also operators that stand in front of a value:

print(-5);  // -5
print(-(3 + 4)); // -7

Number Helpers: abs, min, max

AHA! Lang provides three number builtins that are often useful:

print(abs(-7));    // 7 — absolute value
print(min(3, 9));  // 3 — the smallest
print(max(3, 9));  // 9 — the largest

Chaining Expressions

Expressions can be chained freely — as long as the types match:

let harga = 20000;
let diskon = 10;

// discounted price: 20000 - 10% = 18000
let bayar = harga - (harga * diskon / 100);

print(bayar); // 18000

The computer calculates from left to right following the priority rules: harga * diskon / 100 → 200000 / 100 → 2000, then it's subtracted from harga.

Exercises

1. Print the result of 25 % 7 and explain what it means.
2. Check whether 100 is evenly divisible by 4 (hint: 100 % 4).
3. Create a variable tahun holding your birth year, then compute and print an estimate of your current age.
4. Experiment: what is the result of (1 == 1) * 5 + (2 > 5)? Match it against the explanation above.

On to Working with Strings