Apa iku lambdas lan functional tools map/filter/reduce?

Question

Accepted Answer

A **lambda** yaiku fungsi cilik, anonymous, single-expression. **`map`**, **`filter`**, lan **`reduce`** yaiku functional tools sing apply fungsi ing saindening iterable. Menang-menang iku enable functional style — nanging Python asring milih comprehensions kanggo tugas sing padha.

## Lambda — inline anonymous functions

```python
# a lambda is a one-line function with no name
square = lambda x: x ** 2
square(5)                      # 25

# equivalent named function:
def square(x): return x ** 2
```

Lambdas kuminclong minangka **inline arguments** kanggo fungsi liyane, utamane minangka sort/filter keys:

```python
people.sort(key=lambda p: p.age)            # sort by an attribute
sorted(words, key=lambda w: len(w))          # sort by length
max(items, key=lambda x: x.score)            # find max by a criterion
```

## map — apply fungsi kanggo saben element

```python
nums = [1, 2, 3, 4]
list(map(lambda x: x ** 2, nums))   # [1, 4, 9, 16]
# more Pythonic alternative — a comprehension:
[x ** 2 for x in nums]               # [1, 4, 9, 16]
```

## filter — tetepne elements sing nglalui test

```python
list(filter(lambda x: x % 2 == 0, nums))   # [2, 4]
# comprehension equivalent:
[x for x in nums if x % 2 == 0]             # [2, 4]
```

## reduce — fold iterable dadi siji nilai

```python
from functools import reduce
reduce(lambda acc, x: acc + x, nums, 0)     # 10 (sum)
# but built-ins are clearer when they exist:
sum(nums)                                    # 10
```

## The Pythonic preference

```text
For map/filter, COMPREHENSIONS are usually more readable and idiomatic:
  map(f, xs)            →  [f(x) for x in xs]
  filter(pred, xs)      →  [x for x in xs if pred(x)]
Lambdas are best for short inline keys (sort/max/filter), NOT complex logic.
```

Guido (pencipta Python) lan komunitas umumé milih comprehensions tinimbang `map`/`filter` kanggo readability; `reduce` malah dicalekake saka builtins. Nanging lambdas minangka `key=` functions tetep idiomatic lan umum.

## Apa iku penting

Functional tools iki ngidini kowé ngucapake transformations lan filters kanthi ringkas.

Suwéné Python *bisa* ditulis kanthi functional, pilihan idiomatic biasané yaiku **comprehension** tinimbang `map`/`filter` kanggo readability, lan built-in (`sum`, `max`, `min`) tinimbang `reduce`.

Kanggé lambdas pancen kuminclong yaiku minangka fungsi cilik inline sing dipindhahake menyang `sort`/`max`/`min`/`filter` minangka `key`.

Paham loro-lorone — lan ngerti pilihan Pythonic kanggo comprehensions lan built-ins — mbantu kowé nulis kode sing bersih, idiomatic lan maca functional-style code sing ana ing real projects.