How to make tail function return what I need?












0















I need to encode list in OCaml. Command: encode ['a','a','b','b','b','c'];; have to return [(2,'a');(3,'b');(1,'c')]



Now I have this function:



let encode list =

let rec encodeHelper list acc = match list with

    |  -> 

    | head ::  -> (1, head) :: 

    | head :: headNext :: tail -> if (head = headNext) then encodeHelper (headNext :: tail) (acc + 1)

                                    else (acc, head) :: encodeHelper (headNext :: tail) acc

in encodeHelper list 1

;;


But it returns:




  • : (int * (char * char * char * char * char * char)) list =
    [(1, ('a', 'a', 'b', 'b', 'b', 'c'))]






function functional-programming ocaml







share|improve this question



























    0















    I need to encode list in OCaml. Command: encode ['a','a','b','b','b','c'];; have to return [(2,'a');(3,'b');(1,'c')]



    Now I have this function:



    let encode list =
    
let rec encodeHelper list acc = match list with
    
    |  -> 
    
    | head ::  -> (1, head) :: 
    
    | head :: headNext :: tail -> if (head = headNext) then encodeHelper (headNext :: tail) (acc + 1)
    
                                    else (acc, head) :: encodeHelper (headNext :: tail) acc
    
in encodeHelper list 1
    
;;


    But it returns:




    • : (int * (char * char * char * char * char * char)) list =
      [(1, ('a', 'a', 'b', 'b', 'b', 'c'))]






    function functional-programming ocaml







    share|improve this question

























      0












      0








      0








      I need to encode list in OCaml. Command: encode ['a','a','b','b','b','c'];; have to return [(2,'a');(3,'b');(1,'c')]



      Now I have this function:



      let encode list =
      
let rec encodeHelper list acc = match list with
      
    |  -> 
      
    | head ::  -> (1, head) :: 
      
    | head :: headNext :: tail -> if (head = headNext) then encodeHelper (headNext :: tail) (acc + 1)
      
                                    else (acc, head) :: encodeHelper (headNext :: tail) acc
      
in encodeHelper list 1
      
;;


      But it returns:




      • : (int * (char * char * char * char * char * char)) list =
        [(1, ('a', 'a', 'b', 'b', 'b', 'c'))]






      function functional-programming ocaml







      share|improve this question














      I need to encode list in OCaml. Command: encode ['a','a','b','b','b','c'];; have to return [(2,'a');(3,'b');(1,'c')]



      Now I have this function:



      let encode list =
      
let rec encodeHelper list acc = match list with
      
    |  -> 
      
    | head ::  -> (1, head) :: 
      
    | head :: headNext :: tail -> if (head = headNext) then encodeHelper (headNext :: tail) (acc + 1)
      
                                    else (acc, head) :: encodeHelper (headNext :: tail) acc
      
in encodeHelper list 1
      
;;


      But it returns:




      • : (int * (char * char * char * char * char * char)) list =
        [(1, ('a', 'a', 'b', 'b', 'b', 'c'))]






      function functional-programming ocaml




      function functional-programming ocaml






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Nov 13 '18 at 19:04









      IlyaIlya

      335




      335
























          1 Answer
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          Your test data as shown at the top is not in the right form.



          A list in OCaml has elements separated by semicolons (;). Your test data is using commas instead (,). Commas are used for tuples, which is why you're seeing a tuple in your result.



          If you change , to ; in your test data you should see something closer to what you're looking for. There is at least one problem left to fix (in my testing).






          share|improve this answer























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            active

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            1














            Your test data as shown at the top is not in the right form.



            A list in OCaml has elements separated by semicolons (;). Your test data is using commas instead (,). Commas are used for tuples, which is why you're seeing a tuple in your result.



            If you change , to ; in your test data you should see something closer to what you're looking for. There is at least one problem left to fix (in my testing).






            share|improve this answer




























              1














              Your test data as shown at the top is not in the right form.



              A list in OCaml has elements separated by semicolons (;). Your test data is using commas instead (,). Commas are used for tuples, which is why you're seeing a tuple in your result.



              If you change , to ; in your test data you should see something closer to what you're looking for. There is at least one problem left to fix (in my testing).






              share|improve this answer


























                1












                1








                1







                Your test data as shown at the top is not in the right form.



                A list in OCaml has elements separated by semicolons (;). Your test data is using commas instead (,). Commas are used for tuples, which is why you're seeing a tuple in your result.



                If you change , to ; in your test data you should see something closer to what you're looking for. There is at least one problem left to fix (in my testing).






                share|improve this answer













                Your test data as shown at the top is not in the right form.



                A list in OCaml has elements separated by semicolons (;). Your test data is using commas instead (,). Commas are used for tuples, which is why you're seeing a tuple in your result.



                If you change , to ; in your test data you should see something closer to what you're looking for. There is at least one problem left to fix (in my testing).







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Nov 13 '18 at 19:25









                Jeffrey ScofieldJeffrey Scofield

                47.4k24979




                47.4k24979






























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