Implementation with existential qualification

Signed-off-by: mat tso <mat-tso@topmail.ie>
Implementation using Data.Dynamic

Signed-off-by: mat tso <mat-tso@topmail.ie>
Implementation with (nearly) plain haskell

Signed-off-by: mat tso <mat-tso@topmail.ie>
Update Readme

Signed-off-by: mat tso <mat-tso@topmail.ie>