Maxima and minima

Collection.fs

open FSharpPlus
open FSharpPlus.Operators

module Collection=
    let inline maximaBy (projection: 'T->'Key) (source: '``Collection<'T>``) : '``Collection<'T>``=
        let sorted = sortByDescending projection source
        match tryHead sorted with
        | None -> sorted
        | Some max -> takeWhile ((compare <| projection max) >> (=) 0 << projection) sorted

    let inline minimaBy (projection: 'T->'Key) (source: '``Collection<'T>``) : '``Collection<'T>``=
        let sorted = sortBy projection source
        match tryHead sorted with
        | None -> sorted
        | Some min -> takeWhile ((compare <| projection min) >> (=) 0 << projection) sorted

List.fs

module List=
    let maxima l=
        let sorted = List.sortDescending l
        match sorted with
        | []|[_] -> sorted
        | max::_ -> List.takeWhile ((compare max) >> (=) 0) sorted
    let minima l=
        let sorted = List.sort l
        match sorted with
        | []|[_] -> sorted
        | min::_ -> List.takeWhile ((compare min) >> (=) 0) sorted

    let maximaBy projection l=
        let sorted = List.sortByDescending projection l
        match sorted with
        | []|[_] -> sorted
        | max::_ -> List.takeWhile ((compare <| projection max) >> (=) 0 << projection) sorted
    let minimaBy projection l=
        let sorted = List.sortBy projection l
        match sorted with
        | []|[_] -> sorted
        | min::_ -> List.takeWhile ((compare <| projection min) >> (=) 0 << projection) sorted