Partial

2 snippets across 2 stacks — Python, TypeScript

Also written as Partial

PYPython

functools Module

syntax

from functools import lru_cache, partial, reduce

example

from functools import lru_cache, partial

@lru_cache(maxsize=128)
def fibonacci(n: int) -> int:
    if n < 2:
        return n
    return fibonacci(n - 1) + fibonacci(n - 2)

print(fibonacci(30))
print(fibonacci.cache_info())

# partial: pre-fill arguments
def power(base, exp):
    return base ** exp

square = partial(power, exp=2)
print(square(7))

output

832040
CacheInfo(hits=28, misses=31, maxsize=128, currsize=31)
49

Note lru_cache requires hashable arguments. For unhashable args, consider cachetools or a manual cache. partial is great for adapting callback signatures.

TSTypeScript

Partial<T>

TS · Utility Types

syntax

type Result = Partial<OriginalType>;

example

interface Settings {
  theme: "light" | "dark";
  fontSize: number;
  notifications: boolean;
}

function updateSettings(current: Settings, changes: Partial<Settings>): Settings {
  return { ...current, ...changes };
}

const updated = updateSettings(
  { theme: "light", fontSize: 14, notifications: true },
  { fontSize: 16 } // only need to pass what changed
);

output

// Partial<Settings> makes all properties optional

Note Partial only operates one level deep. Nested objects keep their original required types. For deep partial, you need a custom recursive type or a library utility.