When I read code that uses Select
I think "select-all-where".
When I read code that uses Map
I think "this-to-that" or "apply-to-all".
I can't be the only person that feels the name Select
is confusing.
Map
It's really identical to map from functional languages. The reason it's named Select
is that it's designed to be used as a part of LINQ which uses SQL-like keywords.
from item in collection
where item.Value == someValue
select item.Name
is translated to:
collection.Where(item => item.Value == someValue)
.Select(item => item.Name)
it would be a little inconsistent if Select
was named Map
; something like:
collection.Filter(item => item.Value == someValue)
.Map(item => item.Name)
In fact, many people use LINQ without having heard of functional programming at all. To them, LINQ is a method to retrieve data objects and query them easily (like SQL queries are). To them, Select
and Where
make perfect sense. Much more than Map
and Filter
.
At first Select
seemed little confusing for me too, but it was only a matter of time. Mehrdad tells you a good reason for Select
. Other than that I feel Select
conveys the immutability aspect of Linq
much better. Not that Map
would mean it's mutating the original structure, but Select
states it much clearer. It tells you're not touching the original list but merely selecting from it to form another list.
It goes with other naming as well like Where
. When you call collection.Filter
it gives you an idea that you're filtering on that particular collection, or at least the first time. In the end it's all a matter of getting familiarized. Though in the beginning I was so annoyed by the Linq
namings, now I feel MS team has got it the most correct.
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