selection helper functions not working within `across`

Selection helper functions such as contains and startswith do not work within across. For example:

@chain df begin
  @mutate(across((b, startswith("c")), (minimum, maximum)))
  end

This will throw an error message:

[ Info: transform($(Expr(:escape, :raccoon)), Cols(:b, $(Expr(:escape, :(starts_with("c"))))) .=> reshape([$(Expr(:escape, :minimum)), $(Expr(:escape, :maximum))], 1, 2))
ERROR: ArgumentError: invalid index: Base.Fix2{typeof(startswith), String}(startswith, "c") of type Base.Fix2{typeof(startswith), String}
Stacktrace:
  [1] getindex
    @ ~/.julia/packages/DataFrames/dgZn3/src/other/index.jl:185 [inlined]
  [2] _broadcast_getindex_evalf
    @ ./broadcast.jl:670 [inlined]
  [3] _broadcast_getindex
    @ ./broadcast.jl:643 [inlined]
  [4] (::Base.Broadcast.var"#29#30"{Base.Broadcast.Broadcasted{Base.Broadcast.Style{Tuple}, Nothing, typeof(getindex), Tuple{Base.RefValue{DataFrames.Index}, Tuple{Symbol, Base.Fix2{typeof(startswith), String}}}}})(k::Int64)
    @ Base.Broadcast ./broadcast.jl:1075
  [5] ntuple
    @ ./ntuple.jl:49 [inlined]
  [6] copy
    @ ./broadcast.jl:1075 [inlined]
  [7] materialize
    @ ./broadcast.jl:860 [inlined]
  [8] getindex
    @ ~/.julia/packages/DataFrames/dgZn3/src/other/index.jl:232 [inlined]
  [9] names(df::DataFrame, cols::Cols{Tuple{Symbol, Base.Fix2{typeof(startswith), String}}})
    @ DataFrames ~/.julia/packages/DataFrames/dgZn3/src/abstractdataframe/abstractdataframe.jl:102
 [10] broadcast_pair(df::DataFrame, p::AbstractVecOrMat{<:Pair})
    @ DataFrames ~/.julia/packages/DataFrames/dgZn3/src/abstractdataframe/selection.jl:274
 [11] #548
    @ ~/.julia/packages/DataFrames/dgZn3/src/abstractdataframe/selection.jl:1286 [inlined]
 [12] map(f::DataFrames.var"#548#549"{DataFrame}, t::Tuple{Colon, Matrix{Pair{DataAPI.BroadcastedSelector{Cols{Tuple{Symbol, Base.Fix2{typeof(startswith), String}}}}}}})
    @ Base ./tuple.jl:222
 [13] select(::DataFrame, ::Any, ::Vararg{Any}; copycols::Bool, renamecols::Bool, threads::Bool)
    @ DataFrames ~/.julia/packages/DataFrames/dgZn3/src/abstractdataframe/selection.jl:1285
 [14] #transform#551
    @ ~/.julia/packages/DataFrames/dgZn3/src/abstractdataframe/selection.jl:1365 [inlined]
 [15] transform(df::DataFrame, args::Any)
    @ DataFrames ~/.julia/packages/DataFrames/dgZn3/src/abstractdataframe/selection.jl:1365
 [16] top-level scope
    @ REPL[27]:476

TidierOrg / Tidier.jl

selection helper functions not working within `across` #24