json utilities
value |> SafeDecode.at ["name"] (SafeDecode.string "")
value |> SafeDecode.at ["age"] (SafeDecode.string 0)
value |> SafeDecode.at ["isValid"] (SafeDecode.bool False)
value |> SafeDecode.at ["roles"] (SafeDecode.list (SafeDecode.string ""))
obj |> SafeDecode.valueAt ["object"]decode to json value
decoder and default value