# Arraylist full of functions?
**URL:** https://discourse.processing.org/t/arraylist-full-of-functions/10786
**Category:** Coding Questions
**Created:** [April 30, 2019, 4:14pm UTC](https://discourse.processing.org/t/arraylist-full-of-functions/10786 "2019-04-30T16:14:45Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@DerekCresswell](https://discourse.processing.org/u/DerekCresswell)
#### Post date: [April 30, 2019, 4:14pm UTC](https://discourse.processing.org/t/arraylist-full-of-functions/10786/1 "2019-04-30T16:14:45Z")
I need to store a list of functions that I can execute from said array.
I also need to be able to pass them as variables.
Lambda doesn’t seem to work in processing. How can I do this?
Thanks!
---
### Author:  [@GoToLoop](https://discourse.processing.org/u/GoToLoop)
#### Post date: [April 30, 2019, 6:31pm UTC](https://discourse.processing.org/t/arraylist-full-of-functions/10786/2 "2019-04-30T18:31:31Z")
> [@Function as argument of another function](https://discourse.processing.org/t/function-as-argument-of-another-function/6383/4):
>
> I’ve wet my feet a little on the Java package [java.util.function](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/function/package-summary.html) by instantiating a [Predicate](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/function/Predicate.html) and passing it as an argument at these 2 old sketch links below: crazy_face[Forum.Processing.org/two/discussion/21761/querying-arraylist#Item\_2](http://Forum.Processing.org/two/discussion/21761/querying-arraylist#Item_2)[Forum.Processing.org/two/discussion/22823/how-to-implement-this-method#Item\_2](http://Forum.Processing.org/two/discussion/22823/how-to-implement-this-method#Item_2) Of course it’s not even close to an actual lambda -\> syntax. But it’s as far as we can go under the PDE. roll_eyes
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### Author:  [@humayung](https://discourse.processing.org/u/humayung)
#### Post date: [April 30, 2019, 7:02pm UTC](https://discourse.processing.org/t/arraylist-full-of-functions/10786/3 "2019-04-30T19:02:47Z")
i dont know if you have to use processing, but if you really need lambda expression try using processing as java library from another ide
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### Author:  [@clankill3r](https://discourse.processing.org/u/clankill3r)
#### Post date: [April 30, 2019, 8:31pm UTC](https://discourse.processing.org/t/arraylist-full-of-functions/10786/4 "2019-04-30T20:31:33Z")
Can you list all input parameters and all return types.
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### Author:  [@DerekCresswell](https://discourse.processing.org/u/DerekCresswell)
#### Post date: [May 1, 2019, 9:17pm UTC](https://discourse.processing.org/t/arraylist-full-of-functions/10786/5 "2019-05-01T21:17:13Z")
No inputs, all floats.
---
### Author:  [@monkstone](https://discourse.processing.org/u/monkstone)
#### Post date: [May 2, 2019, 1:01pm UTC](https://discourse.processing.org/t/arraylist-full-of-functions/10786/6 "2019-05-02T13:01:36Z")
[Sam Pottinger](https://github.com/sampottinger/processing) has done an amazing job in updating processing, not only to update to OpenJDK11, but also to support java 8 syntax in the processing ide. I’m sure he would welcome your support. Here is an example using lambda syntax in the processing ide.
```java
interface MyFunction {
float calculate(float x);
}
float[] values = new float[2];
void setup() {
// lambda expression to define the calculate method
MyFunction doubling = (float x)->x * 2;
values[0] = doubling.calculate(5);
values[1] = doubling.calculate(12);
display();
}
void display() {
println(values[0], values[1]);
}
```
The code can be even more elegant in [JRubyArt](https://ruby-processing.github.io/JRubyArt/)
```ruby
attr_reader :values
def setup
# lambda expression to define the calculate method
doubling = ->(x) { x * 2 }
@values = [5.0, 12.0].map { |x| doubling.call(x) }
display
end
def display
puts values
end
```
---
### Author:  [@monkstone](https://discourse.processing.org/u/monkstone)
#### Post date: [May 2, 2019, 2:14pm UTC](https://discourse.processing.org/t/arraylist-full-of-functions/10786/7 "2019-05-02T14:14:22Z")
Or as GoToLoop has already posted for the faint hearted see [Function as argument of another function](https://discourse.processing.org/t/function-as-argument-of-another-function/6383/4), but the update to jdk8 syntax is somewhat overdue.