[jb_s]

Those are some huge ternary ifs

I really wish Typescript had a great pattern matching system. It would be very nice indeed for structural typing, everything would be easier to read, probably some ways to add more power/expressivity, etc.

eg

    type GetOptions<T> =
      // Part 1: responsible for applying explicit type parameter to function arguments, if object { queryFnData: TQueryFnData, error: TError, data: TData }
      T extends {
        queryFnData: infer TQueryFnData
        error?: infer TError
        data: infer TData
      }
        ? UseQueryOptionsForUseQueries<TQueryFnData, TError, TData>
        : T extends { queryFnData: infer TQueryFnData; error?: infer TError }
        ? UseQueryOptionsForUseQueries<TQueryFnData, TError>
        : T extends { data: infer TData; error?: infer TError }
        ? UseQueryOptionsForUseQueries<unknown, TError, TData>
        : // Part 2: responsible for applying explicit type parameter to function arguments, if tuple [TQueryFnData, TError, TData]
        T extends [infer TQueryFnData, infer TError, infer TData]
        // ...

becomes

    type GetOptions<T> =
      // Part 1: responsible for applying explicit type parameter to function arguments, if object { queryFnData: TQueryFnData, error: TError, data: TData }
      T extends match { 
          { queryFnData: infer TQueryFnData, error?: infer TError, data: infer TData } => UseQueryOptionsForUseQueries<TQueryFnData, TError, TData>
          { queryFnData: infer TQueryFnData; error?: infer TError } => UseQueryOptionsForUseQueries<TQueryFnData, TError>,
          { data: infer TData; error?: infer TError }               => UseQueryOptionsForUseQueries<unknown, TError, TData>,
          [infer TQueryFnData, infer TError, infer TData]           => UseQueryOptionsForUseQueries<TQueryFnData, TError, TData>
          [infer TQueryFnData, infer TError]                        => UseQueryOptionsForUseQueries<TQueryFnData, TError>
          // ...
      }

or even, to make the top level way easy to understand in this case:

    type GetOptions<T> =
      T extends match { 
          Part1 => Part1Match
          Part2 => Part2Match
          Part3 => Part3Match
      }

where Part1Match etc are themselves pattern matches, so you can compose them like functions.