python-scala-syntax-mapping

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# Python to Scala Syntax Mapping

## Variable Declarations

| Python | Scala |
|--------|-------|
| `x = 5` | `val x = 5` (immutable) or `var x = 5` (mutable) |
| `x: int = 5` | `val x: Int = 5` |
| `x, y = 1, 2` | `val (x, y) = (1, 2)` |

Prefer `val` over `var` unless mutation is required.

## Type Mappings

| Python | Scala |
|--------|-------|
| `int` | `Int` |
| `float` | `Double` |
| `str` | `String` |
| `bool` | `Boolean` |
| `None` | `None` (of type `Option`) or `null` |
| `list[T]` | `List[T]` or `Seq[T]` |
| `dict[K, V]` | `Map[K, V]` |
| `set[T]` | `Set[T]` |
| `tuple[A, B]` | `(A, B)` or `Tuple2[A, B]` |
| `Optional[T]` | `Option[T]` |

## Control Flow

### Conditionals

```python
# Python
if x > 0:
    result = "positive"
elif x < 0:
    result = "negative"
else:
    result = "zero"
```

```scala
// Scala - if is an expression
val result = if (x > 0) "positive"
             else if (x < 0) "negative"
             else "zero"
```

### Loops

```python
# Python for loop
for i in range(10):
    print(i)

for item in items:
    process(item)

for i, item in enumerate(items):
    print(f"{i}: {item}")
```

```scala
// Scala equivalents
for (i <- 0 until 10) println(i)

for (item <- items) process(item)

for ((item, i) <- items.zipWithIndex) println(s"$i: $item")
```

### While loops

```python
# Python
while condition:
    do_something()
```

```scala
// Scala
while (condition) {
  doSomething()
}
```

## Comprehensions

```python
# Python list comprehension
squares = [x ** 2 for x in range(10)]
evens = [x for x in numbers if x % 2 == 0]
pairs = [(x, y) for x in xs for y in ys]
```

```scala
// Scala for-comprehensions or map/filter
val squares = (0 until 10).map(x => x * x).toList
val evens = numbers.filter(_ % 2 == 0)
val pairs = for { x <- xs; y <- ys } yield (x, y)
```

## Functions

```python
# Python
def add(a: int, b: int) -> int:
    return a + b

# Lambda
square = lambda x: x ** 2

# Default arguments
def greet(name: str, greeting: str = "Hello") -> str:
    return f"{greeting}, {name}!"
```

```scala
// Scala

From benchflow-ai/skillsbench, Apache-2.0.

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