Comprehensions in Python

Python’s comprehensions (list, generator, dictionarry) are neat, however coming from Haskell I miss let.

funItems = [ item | itemId <- ids, let item = getItem itemId, isFun item ]

In the meantime, I have seen in python

fun_items = [ get_item(item_id) for item_id in ids if is_fun(get_item(item_id)) ]

Needless to say, even without get_item being an expensive operation, this feels bad. After thinking about it for a while I came up with and alternative.

fun_items = [ item for item_id in ids for item in (get_item(item_id),) if is_fun(item) ]
# or with nesting
fun_items = [ item for item in (get_item(item_id) for item_id in ids) if is_fun(item) ]

Though it is a bit longer 🤔. You win some, you lose some, I guess. 🤷

Still feels better than nesting.