haskell - What does [safe] marker mean in ghci? -

- 

prelude data.void> :info void data void       -- defined in `data.void' instance [safe] eq void -- defined in `data.void' instance [safe] ord void -- defined in `data.void' instance [safe] read void -- defined in `data.void' instance [safe] show void -- defined in `data.void'

what [safe] mean?

it means datatype defined in module defined using safe extension. can find details of extension in user guide.

in fact, can test defining module using safe extension:

{-#language safe#-}  data test = test deriving (eq, show)

and trying out in ghci:

λ> :i test data test = test     instance [safe] eq test  instance [safe] show test

but note in current ghc (7.10.2), safe extension cannot relied of trust guarantee because of this ghc bug.


Comments

Post a Comment

Popular posts from this blog

java - unable show chart in xls document using jasper reports -

-
Image
i new jasper reports . able export data through jasper reports excel sheet. when created pie chart in ireports , showing on preview. when write below code in jsp file view report in jasperviewer , shows data along chart. when try save document (that in jasperviewer, gives many ways of saving report either in pdf or rtf or xls) xls error came in console net.sf.jasperreports.engine.jrexception: cell cannot added. however when remove chart .jrxml file, able export data excel file. read jr chart inserted image in excel document. xls document not taking images. below jsp file: <%@ page language="java" contenttype="text/html; charset=iso-8859-1" pageencoding="iso-8859-1" import="java.sql.*,java.util.*, net.sf.jasperreports.engine.*,java.io.*, net.sf.jasperreports.engine.design.*, net.sf.jasperreports.view.jasperviewer" %> <!doctype html public "-//w3c//dtd html 4.01 transitional//en" "http://www.w3.org/tr/html...
Read more

java.lang.RuntimeException: Could not generate dummy secret at sun.security.ssl.RSAClientKeyExchange.<init> -

-
i working on java ee application (netbeans ide 8.0.2, glassfish 4.1, jdk 1.8.0_45). the access pages of application should secured https, modified web.xml : <security-constraint> <web-resource-collection> <url-pattern>/*</url-pattern> </web-resource-collection> <user-data-constraint> <description/> <transport-guarantee>confidential</transport-guarantee> </user-data-constraint> </security-constraint> when deploy & start glassfish via netbeans can access application via https://localhost:8181/myapp/ when bundle application in .war file , deploy manually copy of same glassfish installation files netbeans uses, exception while trying connect application: warning (35) grizzly0013: exception during filterchain execution java.lang.runtimeexception: not generate dummy secret @ sun.security.ssl.handshaker.checkthrown(handshaker.java:1429) @ sun.security.ssl.sslen...
Read more

javascript - How to change image src on success AJAX -

-
the form: <form action="/user/updateprofilepicture" id="uploadphotoform" method="post" enctype="multipart/form-data"> <button class="btn btn-onetraffic btn-responsive btn-large">+change photo</button> <input class="btn btn-onetraffic btn-responsive btn-large" style="opacity: 0; height: 34px; margin-top: -34px;" type="file" id="uploadphoto" name="file" accept="image/*"> </form> div want image source changed: <div id="img-container"> <img id="upslika" src="#"/> </div> i images url server through json i tried : success:function(){ console.log("success"); $("#upslika").attr("src", res.pictureurl); }, res response the success callback must this: success: function (res) { ...
Read more