Straightforward Functional Programming Examples in Julia

Hi Wolf, not sure what you are testing. Note that the timing depends on how you test it.

The any(x -> x < 3, numbers) might look slow if you use @time, but that's because the anonymous function keeps getting recompiled for every call. Maybe that's what you mean?

You can easily bypass this by placing it inside another function. Also you can use BenchmarkTools.@btime instead to ignore the compilation time.

julia> numbers = [1, 2, 3, 4, 5];

julia> @time any(x -> x < 3, numbers)
  0.006801 seconds (2.74 k allocations: 183.680 KiB, 99.01% compilation time)
true

julia> @time any(numbers .< 3)
  0.000012 seconds (3 allocations: 128 bytes)
true

julia> any_less(numbers, value) = any(x -> x < value, numbers)
any_less (generic function with 1 method)

julia> @time any_less(numbers, 3) # first call compiles the `any_less`
  0.009657 seconds (6.90 k allocations: 456.047 KiB, 99.76% compilation time)
true

julia> @time any_less(numbers, 3) # now it's fast
  0.000005 seconds
true

But perhaps you are talking about something else?

I had made a mistake, wrote my code as a script as such:

using BenchmarkTools

numbers = rand(100)
num = 0.001

println("Size of test array $(length(numbers))")
println("Roughly $(num*100)% of entries satisfy condition (entry < $num)")
println()

println("result with <($num)")
@btime any(<(num), numbers)

println("result with x -> x < $num")
@btime any(x -> x < num, numbers)

println("numbers .< $num")
@btime any(numbers .< num)

However this has to allocate space for the array and number for each call to any. In the any(x -> x < num) case it even has to allocate num for each iteration done by any.

This lead to confusion on my part as any(x -> x < num) slowed down more than the other approaches when more iterations were required to find a match which I initially did not expect.