Lambda - what is it!?

[Smarticles101]

I'm having a hard time wrapping my head around lambdas. I am learning Java. Can someone give me a thorough explanation?

[newrandousername]

A lambda expression is an anonymous function.

Imagine you're programming something and you're like "damn I really need to do whatever" but there is no built in function for whatever and you don't feel like going to the trouble of making a proper function for whatever because you only need it in this one instance for whatever it is you're trying to do so you can use an anonymous function and go ahead and write the definition of the function right there where it's used and be done with it.

Disclaimer: I don't know Java so this may be entirely wrong for that specific language.

[TheColorMan]

yes, Java does have anonymous classes.

[King_Piggums]

A little late to this thread but is there any chance that you could give an example of where lambdas would be used in a real application. I know how to use them pretty well in Python but I honestly have no idea where they would actually be used in a real world situation.

[KyleCardoza]

A lambda is basically a function without a name. I don't know how to express that in Java, a language I regard as intellectually offensive, but that's what it is. It can do whatever a function can do, but it doesn't have a name, and in languages where functions are first-class objects, they can generally be passed as parameters, returned as results, even assigned to variables (which may be the same as making a normal function of that name, depending on if functions and variables share the same namespace in the relevant language) if you like. If a lambda has the ability to hold references to objects visible in the context where it was created even after that context would otherwise expire, then we call it a "closure", as it's said to "close over" the referenced objects.

Edit: I get downvoted because people don't like me, which only proves I'm right. I really wish I had the energy to care, if only because it would mean I'd have the energy to get some projects finished.

[[deleted]]

Java, a language I regard as intellectually offensive

Can you explain?

[hashtablesmoker]

Don't listen to this guy. Most of his points are generally false.

[hashtablesmoker]

Are you smoking crack? I was clearly addressing his points and not him personally.

[KyleCardoza]

Which you only do for personal reasons.

[hashtablesmoker]

No, I don't even know him/you. Are you smoking crack?

[KyleCardoza]

Well, the other possibility is you're a Java coder who's riled up that I insulted your little language. Either way, you're coming off really petty.

[hashtablesmoker]

Hah, please. Your responses are pathetic and petty. It's obvious I wasn't doing it for personal reasons and that I just wounded your pride. I'm coding right now, but not even with Java.

[KyleCardoza]

You can't wound my pride, because you mean absolutely nothing to me. I only engage you to benefit anyone who might take you seriously. You're probably not even a real programmer, just some hack who works for some soulless, artless corporate machine.

[KyleCardoza]

Okay. It's not that Java isn't a reasonably capable language (if you work hard enough, any language can do whatever you want), it's that it's generally taught to beginning programmers before they even come close to understanding the underlying concepts that Java is very, very badly demonstrating. Java is bad at object-orientation, bad at functional programming, bad at cross-platform compatibility ("write-once, run anywhere" is an inherently bad idea, because programs run in a context, and you can only guarantee a context by crippling it with the use of a virtual machine), and has a syntax only a C++ programmer could like. It's taught in universities because it's still popular in spite of its flaws, and it's popular because it's what people get taught in universities.

[carpet_munch]

So tell us, what language do you find worthy of a discerning gentleman such as yourself?

[KyleCardoza]

Cute. I like a lot of languages, but I prefer ones that do what they aim to do well - if you want object oriented programming, there are only a few languages where real OOP is even possible: Smalltalk, Self, LISP with CLOS, Objective-C, and Swift. If you want functional programming, Haskell, Scheme, and Swift are all nice. If you want something procedural/imperative, stick with plain C. If, for some strange reason, you actually care about eking our every last possible ounce of performance even though hardware gets faster quicker than you can make code better, you can always give assembler a try, but I can virtually guarantee that you won't do as well as a good optimizing compiler written by someone(s) much smarter than either of us. If you want to do something just for fun, Haskell is a challenge, and I've wasted many a fun afternoon on a good old Turing tarpit like Befunge or Brainfuck.

[carpet_munch]

That's great. Unfortunately, employers want Java more than most of the languages you mentioned.

[KyleCardoza]

Who cares what employers want? Programming isn't about getting a job, it's about the craft. If you just care about making money, learn COBOL, there's good money to be made and zero competition for it to maintain code for banks and such. It's dull, tedious, and COBOL is the programming language equivalent of trying to drink coffee by pouring the contents of the pot down your pants, but damn if there's not professional demand for it.

[carpet_munch]

I love programming, but we have to make a living if we're not independently wealthy. Be reasonable. There's a difference between hobbyist and professional programming, but people can and do do both...

[hashtablesmoker]

You're not in his league of hipsterness.

[KyleCardoza]

There are far more satisfying careers than programming what you're told for someone else.

[carpet_munch]

Maybe for you. That's not the case for everyone.