Haskell Map definition Error -


I am recently for Haskell and I have a problem while trying to write my definition of the map function. Example: Mapi (& gt; 2) [1,2,3,4,5] = [false, false, true, true] 

  Mapi _ [] = 0 mpeg F (X : Xs) = [fx] ++ mapi f xs   
 When I try this I get an error:  
  any number (number [bool] ]]) Potential Fix: Potential Fix: (Name [Child]) Add an example announcement for: Mapi (> 2) [1, 2, 3, 4, ...] Equation for `this': this = mpei (& gt; 2) [1, 2, 3, ....]   
 I know that it is related: mapi _ [ ] = 0 but I do not know the problem I found it, I mean, he has to stop at []!  
  
 
 
 You accidentally replaced  0  with  []  In the first case it should be  
  mapi _ [] = [] mpeg f (x: x) = [fx] ++ mpeg fx   
 If you type a signature, it helps:  
  mapi :: (a-> b) - & gt; [A] - & gt; [B]   
 then  Mapi  is considered to return the function, a list, and a list  0  is not a list Is, but  []  is.  
 Any example ....  
 The error message is saying that this will be done in  0  in a  [bool]  It was trying to change, which is not it a numerical type, it is stuck because the  Num  class by  fromInteger  function, but  [bool]  . (Each  Num  example should have a  to the integer  function so that the written words containing the integers like  0  and  23  That type of value can stand for.)  
 This shows that you can make an example for  Num [Bool]  so that it can be compiled. This is not a good idea, and this particular error message is often due to a type of mismatch rather than an actual example example - it is worth remembering next time.

Comments

Post a Comment

Popular posts from this blog

Verilog Error: output or inout port "Q" must be connected to a structural net expression -

I get the error every time, I try to compile. I'm not sure why anyone can help is? I'm new to verilog. Module D_FF (clerk, d, reset_n, q); Input D, Clack, reset_en; Output Q; reg Q; lab4_gdl f1 (.lk (~ clk), d (d), .q.m (qm)); lab4_GDL f2 (.Clk (Clk), D (QM), .Q (Q)); Always start at @ (posedge clk, neggeous reset_n) (Reset_n == 0) Q & lt; = 0; Other questions & lt; = D; Edit End: The problem is what we are asking to do: In this section, you apply the memory / registration circuit on the AlterEdie 2 board. will do. The circuit has the following specifications: The present value of swift SW15-0 on the D2 board should be shown in four hexadecimal four sections of HEX3-0. This part of the circuit will be combination logic. To use an active-less asynchronous reset and KEY1 to use KEY0 as the clock input, you must store SW15-0in in a 16-bit register in the value The register should be enabled to have a 16-bit positive edge, which uses the embedded D flip-flo
Read more

jasper reports - How to center align barcode using jasperreports and barcode4j -

I use iReport 5.5.0 . How to align a barcode component to the center The relevant piece of my jrxml is below & Lt; JR: Code 128 xmlns: JR = "http://jasperreports.sourceforge.net/jasperreports/components" xsi: schemaLocation = "http://jasperreports.sourceforge.net/jasperreports/components http: //jasperreports.sourceforge Purge / xsd / components.xsd "textPosition =" bottom "& gt; & Lt; Jr: codeExpression & gt; & Lt; [CDATA [$ F {number}]] & gt; & Lt; / Jr: codeExpression & gt; & Lt; / Jr: Code 128 & gt; & Lt; / componentElement & gt; "Text" itemprop = "text"> Create a style after this, it is called "barcode", like: & lt; Style name = "barcode" fontName = "Helvetica" fONTSIZE = "10" hAlign = "center" valign = "center" /> and set the property of your barcode element to "barcode".
Read more

c# - ASP.NET MVC - Attaching an entity of type 'MODELNAME' failed because another entity of the same type already has the same primary key value -

In brief, the wrapper module is inserted during posting and the status of an entry is changed to 'modified' . Before changing the state, the state is set to 'separate', but calling attachments () causes the same error to be thrown away. I am using EF 6. Model / wrapper class public class avi model {public A is a {get; Set; } Public listing & lt; B & gt; B {received; Set; } Public cc {receipt; Set; }} Administrator edit public functioning (int? id) {if (id == null) {new HttpStatusCodeResult (HttpStatusCode.BadRequest); } If (! Conveyor Access (id.Value)) new HTTPTitus code result (HTTP status code. Forbidden); Var aViewModel = new AViewModel (); aViewModel.A = db.As.Find (id); If (aViewModel.Receipt == zero) {return HttpNotFound (); } aViewModel.b = db.Bs.Where (x => x.aid == id.Value) .Oolist (); AViewModel.Vendor = db.Cs.Where (x => x.cid == aViewModel.a.cID) .FirstOrDefault (); See Return (aViewModel); } [HTPFost] [Valid AntitiferousTeacon
Read more