How to fix “pattern-matching is not exhaustive”,












0















I want to write function that will add two elements of type eval



type eval = Num of float | Neg | Add | Sub | Mul | Div;;


OCaml compiler gives me this warning, but I do not know exactly what it wants. It works, but I want to make it without this warning.



# let (+++) (Num a) (Num b) =

  match (Num a), (Num b) with

  | (Add|Neg|Sub|Mul|Div), _ -> failwith "01"

  | _, (Add|Neg|Sub|Mul|Div) -> failwith "02"

  | _, _ -> Num (a +. b)

  ;;        

Warning 8: this pattern-matching is not exhaustive.

Here is an example of a case that is not matched:

(Neg|Add|Sub|Mul|Div)

Warning 8: this pattern-matching is not exhaustive.

Here is an example of a case that is not matched:

(Neg|Add|Sub|Mul|Div)

val ( +++ ) : eval -> eval -> eval = <fun>





function functional-programming ocaml







share|improve this question




















  • 1





    Try calling your +++ function with anything other than a Num. Your failwith "01" and failwith "02" cases will never be reached.

    – sepp2k
    Nov 28 '18 at 14:29
















0















I want to write function that will add two elements of type eval



type eval = Num of float | Neg | Add | Sub | Mul | Div;;


OCaml compiler gives me this warning, but I do not know exactly what it wants. It works, but I want to make it without this warning.



# let (+++) (Num a) (Num b) =

  match (Num a), (Num b) with

  | (Add|Neg|Sub|Mul|Div), _ -> failwith "01"

  | _, (Add|Neg|Sub|Mul|Div) -> failwith "02"

  | _, _ -> Num (a +. b)

  ;;        

Warning 8: this pattern-matching is not exhaustive.

Here is an example of a case that is not matched:

(Neg|Add|Sub|Mul|Div)

Warning 8: this pattern-matching is not exhaustive.

Here is an example of a case that is not matched:

(Neg|Add|Sub|Mul|Div)

val ( +++ ) : eval -> eval -> eval = <fun>





function functional-programming ocaml







share|improve this question




















  • 1





    Try calling your +++ function with anything other than a Num. Your failwith "01" and failwith "02" cases will never be reached.

    – sepp2k
    Nov 28 '18 at 14:29














0












0








0








I want to write function that will add two elements of type eval



type eval = Num of float | Neg | Add | Sub | Mul | Div;;


OCaml compiler gives me this warning, but I do not know exactly what it wants. It works, but I want to make it without this warning.



# let (+++) (Num a) (Num b) =

  match (Num a), (Num b) with

  | (Add|Neg|Sub|Mul|Div), _ -> failwith "01"

  | _, (Add|Neg|Sub|Mul|Div) -> failwith "02"

  | _, _ -> Num (a +. b)

  ;;        

Warning 8: this pattern-matching is not exhaustive.

Here is an example of a case that is not matched:

(Neg|Add|Sub|Mul|Div)

Warning 8: this pattern-matching is not exhaustive.

Here is an example of a case that is not matched:

(Neg|Add|Sub|Mul|Div)

val ( +++ ) : eval -> eval -> eval = <fun>





function functional-programming ocaml







share|improve this question
















I want to write function that will add two elements of type eval



type eval = Num of float | Neg | Add | Sub | Mul | Div;;


OCaml compiler gives me this warning, but I do not know exactly what it wants. It works, but I want to make it without this warning.



# let (+++) (Num a) (Num b) =

  match (Num a), (Num b) with

  | (Add|Neg|Sub|Mul|Div), _ -> failwith "01"

  | _, (Add|Neg|Sub|Mul|Div) -> failwith "02"

  | _, _ -> Num (a +. b)

  ;;        

Warning 8: this pattern-matching is not exhaustive.

Here is an example of a case that is not matched:

(Neg|Add|Sub|Mul|Div)

Warning 8: this pattern-matching is not exhaustive.

Here is an example of a case that is not matched:

(Neg|Add|Sub|Mul|Div)

val ( +++ ) : eval -> eval -> eval = <fun>





function functional-programming ocaml




function functional-programming ocaml






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 28 '18 at 21:29









rrauenza

3,53921835




3,53921835










asked Nov 28 '18 at 14:22









IlyaIlya

345




345








  • 1





    Try calling your +++ function with anything other than a Num. Your failwith "01" and failwith "02" cases will never be reached.

    – sepp2k
    Nov 28 '18 at 14:29














  • 1





    Try calling your +++ function with anything other than a Num. Your failwith "01" and failwith "02" cases will never be reached.

    – sepp2k
    Nov 28 '18 at 14:29








1




1





Try calling your +++ function with anything other than a Num. Your failwith "01" and failwith "02" cases will never be reached.

– sepp2k
Nov 28 '18 at 14:29





Try calling your +++ function with anything other than a Num. Your failwith "01" and failwith "02" cases will never be reached.

– sepp2k
Nov 28 '18 at 14:29












1 Answer
1






active

oldest

votes


















2














The non-exhaustive patterns are here:



 let (+++) (Num a) (Num b) = ...


With those pattern, you are making the hypothesis that the argument of +++ are always of the form Num _ without enforcing it in the type system.
If you want to get rid of the warning you should expand the pattern matching to catch all other cases:



 let (+++) x y = match x, y with 

 | ...





share|improve this answer























    Your Answer






    StackExchange.ifUsing("editor", function () {
    StackExchange.using("externalEditor", function () {
    StackExchange.using("snippets", function () {
    StackExchange.snippets.init();
    });
    });
    }, "code-snippets");

    StackExchange.ready(function() {
    var channelOptions = {
    tags: "".split(" "),
    id: "1"
    };
    initTagRenderer("".split(" "), "".split(" "), channelOptions);

    StackExchange.using("externalEditor", function() {
    // Have to fire editor after snippets, if snippets enabled
    if (StackExchange.settings.snippets.snippetsEnabled) {
    StackExchange.using("snippets", function() {
    createEditor();
    });
    }
    else {
    createEditor();
    }
    });

    function createEditor() {
    StackExchange.prepareEditor({
    heartbeatType: 'answer',
    autoActivateHeartbeat: false,
    convertImagesToLinks: true,
    noModals: true,
    showLowRepImageUploadWarning: true,
    reputationToPostImages: 10,
    bindNavPrevention: true,
    postfix: "",
    imageUploader: {
    brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
    contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
    allowUrls: true
    },
    onDemand: true,
    discardSelector: ".discard-answer"
    ,immediatelyShowMarkdownHelp:true
    });


    }
    });














    draft saved

    draft discarded


















    StackExchange.ready(
    function () {
    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53521610%2fhow-to-fix-pattern-matching-is-not-exhaustive%23new-answer', 'question_page');
    }
    );

    Post as a guest















    Required, but never shown

























    1 Answer
    1






    active

    oldest

    votes








    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    2














    The non-exhaustive patterns are here:



     let (+++) (Num a) (Num b) = ...


    With those pattern, you are making the hypothesis that the argument of +++ are always of the form Num _ without enforcing it in the type system.
    If you want to get rid of the warning you should expand the pattern matching to catch all other cases:



     let (+++) x y = match x, y with 
    
 | ...





    share|improve this answer




























      2














      The non-exhaustive patterns are here:



       let (+++) (Num a) (Num b) = ...


      With those pattern, you are making the hypothesis that the argument of +++ are always of the form Num _ without enforcing it in the type system.
      If you want to get rid of the warning you should expand the pattern matching to catch all other cases:



       let (+++) x y = match x, y with 
      
 | ...





      share|improve this answer


























        2












        2








        2







        The non-exhaustive patterns are here:



         let (+++) (Num a) (Num b) = ...


        With those pattern, you are making the hypothesis that the argument of +++ are always of the form Num _ without enforcing it in the type system.
        If you want to get rid of the warning you should expand the pattern matching to catch all other cases:



         let (+++) x y = match x, y with 
        
 | ...





        share|improve this answer













        The non-exhaustive patterns are here:



         let (+++) (Num a) (Num b) = ...


        With those pattern, you are making the hypothesis that the argument of +++ are always of the form Num _ without enforcing it in the type system.
        If you want to get rid of the warning you should expand the pattern matching to catch all other cases:



         let (+++) x y = match x, y with 
        
 | ...






        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Nov 28 '18 at 14:29









        octachronoctachron

        5,2231614




        5,2231614
































            draft saved

            draft discarded




















































            Thanks for contributing an answer to Stack Overflow!


            • Please be sure to answer the question. Provide details and share your research!

            But avoid …



            • Asking for help, clarification, or responding to other answers.

            • Making statements based on opinion; back them up with references or personal experience.


            To learn more, see our tips on writing great answers.




            draft saved


            draft discarded














            StackExchange.ready(
            function () {
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53521610%2fhow-to-fix-pattern-matching-is-not-exhaustive%23new-answer', 'question_page');
            }
            );

            Post as a guest















            Required, but never shown





















































            Required, but never shown














            Required, but never shown












            Required, but never shown







            Required, but never shown

































            Required, but never shown














            Required, but never shown












            Required, but never shown







            Required, but never shown







            -

            Popular posts from this blog

            A CLEAN and SIMPLE way to add appendices to Table of Contents and bookmarks

            Image
            0 I found a lot of questions abount appendices and ToC. Many users want appendices to be grouped in an Appendix part, however some problems arise with ToC, hyperref, PDF viewer bookmarks, and so on. There are different solutions which require extra packages, command patching and other extra code, however none of them satisfies me. I almost found an easy way to accomplish a good result, where appendices are added to bookmarks in the right way and hyperref links point to the right page. However, the number of the "Appendix" part page is wrong (it's the number of appendix A). Is there any EASY way to fix that? This is a MWE: documentclass{book} usepackage[nottoc,notlot,notlof]{tocbibind} usepackage{hyperref} begin{document} frontmatter tableofcontents mainmatter part{First} chapter{...
            Read more

            Calculate evaluation metrics using cross_val_predict sklearn

            Image
            1 In the sklearn.model_selection.cross_val_predict page it is stated: Generate cross-validated estimates for each input data point. It is not appropriate to pass these predictions into an evaluation metric. Can someone explain what does it mean? If this gives estimate of Y (y prediction) for every Y (true Y), why can't I calculate metrics such as RMSE or coefficient of determination using these results? python scikit-learn cross-validation share | improve this question edited Nov 28 '18 at 17:52 desertnaut 20.3k 7 43 79 ...
            Read more

            Insert data from modal to MySQL (multiple modal on website)

            Image
            0 I have problem with inserting data to MySQL from modal. My modal: <a href="#" class="badge badge-pill badge-success">6 komentarzy</a> <a href="#" class="badge badge-pill badge-danger">brak komentarzy</a> <a data-toggle="modal" href="#add_desk_comm_{$desk_['desk_id']}" data-target="#add_desk_comm_{$desk_['desk_id']}" class="ediiit">(dodaj)</a> <div class="modal fade" id="add_desk_comm_{$desk_['desk_id']}" tabindex="-1" role="dialog" aria-labelledby="edit_printer" aria-hidden="true"> <div class="modal-dialog" role="document"> ...
            Read more