From alan-turing-institute/MLJBase.jl#68:

This doesn't work:

@mlj_model mutable struct Bar
    a::Int = -1::(_ > -2)
end

But this does:

@mlj_model mutable struct Bar
    a::Int = (-)(1)::(_ > -2)
end

This needs to be documented in MLJ/docs/src/adding_models_for_general_use and MLJ/docs/src/quick_start_guide_to_adding_models

If I understand it right, check_instances seems to tend to cluster transformers with same types without regard to the list order.
So the results from make_group and BaseEnsemble are also wrong.

Reproduce - Case 1

Code

from mlens.utils import check_instances
from sklearn.preprocessing import (
    StandardScaler as SS, FunctionTransformer as FT)
from xgboost imp

We will probably have to do this sooner or later, although the style may not fit well to document individual PipeOps.

Hi in:
https://sl3.tlverse.org/reference/sl3_task

the valid values for outcome_type, is not documented. After searching on internet, it seems there is no information in any webpage indexed by google. It might be necessary to add which values are acceptable, i.e. "continuous", "binomial", etc....