getAllSubstrings M function | Generate all possible contiguous substring combinations from a string.

getAllSubstrings.pq

let
    /* This was an exercise just for fun. Who knows, it might have a real-world application... */
    /* Generate every possible substring combination from a string */
    getAllSubstrings = (s as text, optional makeDistinct as logical, optional ignoreCase as logical) as list =>
        let
            c = if ignoreCase ?? false then Comparer.OrdinalIgnoreCase else Comparer.Ordinal,
            n = Text.Length(s),
            sub = List.TransformMany(
                {0..n-1},
                each {_+1..n},
                (x, y) => Text.Range(s, x, y-x)
            ),
            ans = if makeDistinct ?? false then List.Distinct(sub, c) else sub
        in
            ans,
     
    /* AllSubstrings */
    EXAMPLE_1 = getAllSubstrings("ABBA"),
    
    /* Distinct Substrings */
    EXAMPLE_2 = getAllSubstrings("ABBa", true),
    
    /* Distinct Substrings, ignoring case */
    EXAMPLE_3 = getAllSubstrings("ABBa", true, true)
in
    EXAMPLE_3