Dataset loading functions should not use macros

[jiahao]

https://github.com/ashryaagr/Fairness.jl/blob/master/src/datasets/datasets.jl has many data loading macros which are simply functions. Best practice for Julia code is to use macros only in situations where code rewriting is necessary.

Would be good to think about a general purpose data loader so that this package can work nicely with other packages such as https://github.com/JuliaStats/RDatasets.jl

[ashryaagr]

I kept the data loading macros to follow the MLJ pattern https://github.com/alan-turing-institute/MLJBase.jl/blob/master/src/data/datasets.jl#L200

But, I agree that using a macro isn't suitable as the data loaders are simply functions. I will think about this and see what's the best thing possible.

The package can already work with general datasets apart from the ones in Fairness/src/datasets/datasets.jl . An example is available at https://www.ashrya.in/Fairness.jl/dev/datasets/#Other-Datasets .
MLJ.OpenML.load can be used to load the datasets.

I can't really think of any functionality that can be provided by writing another general purpose data loader.