In Julia, block passing refers to a technique where a block of code is passed as a function argument. The curly brackets {} are used to define the block of code, and it can be passed to a function as an anonymous function.
Here's an example:
Suppose you want to apply a specific function to a range of numbers. You can use the map function along with block passing to do this in one line of code.
x = [1,2,3,4,5]
map({i -> i^2}, x)
In this example, the block of code enclosed in {} is i -> i^2, which is an anonymous function that squares each element in the input array x. The map function applies this function to each element of the array.
Another example:
Suppose you have a list of words, and you want to select only the words that start with a specific letter. Again, you can use block passing to do this in one line of code:
words = ["apple", "banana", "orange", "peach", "grape"]
filter({w -> w[1] == 'a'}, words)
In this example, the block of code enclosed in {} is w -> w[1] == 'a', which is an anonymous function that checks if the first character of the input string is 'a'. The filter function applies this function to each element of the array words to select only those that satisfy the condition.
In summary, block passing is a convenient technique that can be used to pass a block of code as a function argument in Julia, allowing you to write concise and expressive code.