I wonder why they don't just do `.toString()` on the mapping function and then parse the resulting Javascript into an AST and figure out property accesses from that. At the very least, that'd allow the code to properly throw an error in the event the callback contains any forbidden or unsupported constructs.
Unfortunately, "every object is truthy" and "every object can be coerced to a string even if it doesn't have a meaningful stringifier" are just how JavaScript works and there's not much we can do about it. If not for these deficiencies in JS itself, then your code would be flagged by the TypeScript compiler as having multiple type errors.
On a little less trivial skim over it looks like the intention here isn't to map property-level subsets returned data (e.g., only getting the `FirstName` and `LastName` properties of a larger object); as much as it is to do joins and it's not data entities being provided to the mapping function but RpcPromises so individual property values aren't even available anyway.
So I guess I might argue that map() isn't a good name for the function because it immediately made me think it's for doing a mapping transformation and not for basically just specifying a join (since you can't really transform the data) since that's what map() can do everywhere else in Javascript. But for all I know that's more clear when you're actually using the library, so take what I think with a heaping grain of salt. ;)
That sounds incredibly complicated, and not something we could do in a <10kB library!
The suggestion was to parse _JavaScript_. (That's what `.toString()` on a function does... gives you back the JavaScript.)
It feels like C# has an answer to every problem I’ve ever had with other languages - dynamic loading, ADTs with pattern matching, functional programming, whatever this expression tree is, reflection, etc etc. Yet somehow it’s still a niche language that isn't widely used (outside of particular ecosystems).
I've worked only at startups/small businesses since I graduated university and it's all been in C#.
fucking nice ecosystem
Pi types, existential types and built-in macros to name a few.
You were maybe already getting at it, but as a kitchen sink language the answer is "simplicity". All these diverse language features increase cognitive load when reading code, so it's a complexity/utility tradeoff
If you dare leave the safety of a compiler you'll find that Sublime Merge can still save you when rewriting a whole part of an app. That and manual testing (because automatic testing is also clutter).
If you think it's more professional to have a compiler I'd like to agree but then why did I run into a PHP job when looking for a Typescript one? Not an uncommon unfolding of events.
Granted, I started out on LISP. My version of "easy to read and write" might be slightly masochistic. But I love Perl and Python and Javascript are definitely "you can jump in and get shit done if you have worked in most languages. It might not be idiomatic, but it'll work"...
It does require twice the lines of PHP code to make a Ruby or Python program equivalent, or more if you add phpdoc and static types though, so it is easier to read/write Ruby or Python, but only after learning the details of the language. Ruby's syntax is very expressive but very complex if you don't know it by heart.
Specifically, I'd like to be able to have "inches" as a generic type, where it could be an int, long, float, double. Then I'd also like to have "length" as a generic type where it could be inches as a double, millimeters as a long, ect, ect.
I know they added generic numbers to the language in C# 7, so maybe there is a way to do it?
select(c for c in Customer if sum(c.orders.total_price) > 1000)
Along with https://pypi.org/project/pony-stubs/, you get decent static typing as well. It's really quite something.
It generally unrolls as a `for loop` underneath, or in this case LINQ/SQL.
C# was innovative for doing it first in the scope of SQL. I remember the arrival of LINQ... Good times.
Func<..> is lambda that can only be invoked.
Expression<Func..>> is an AST of a lambda that can be transformed by your code/library.
Since JS doesn't have this, they have to pass in a special placeholder value and try to record what the code is doing to that value.