non-exhaustive-patterns

How to implement a function to change array cells avoiding non-exhaustive pattern errors in haskell? [closed]

Closed . This question needs details or clarity . It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post . Closed 10 months ago . My goal is to write a function called walk, which switches the value of a labyrinth cell with its...

Haskell: Non-exhaustive pattern - Checking if list is ascending

I have no idea why my function doesn't work. I have gone through all the posts about non-exhaustive functions but my functions fulfills all possible options as far as I can see. ascending :: [Int] -> Bool ascending [] = error "Empty list given" ascending [x] = True ascending [x,y] | y>=x = True | x...

Why am I getting “Non-exhaustive patterns in function…” when I invoke my Haskell substring function?

I'm working my way through the book The Haskell Road to Logic, Maths and Programming . (I'm only mid-way through chapter 1, but I'm enjoying it so far and intend to continue.) I've read through the section 1.5 "Playing the Haskell Game" which "consists of a number of further examples to get you...

Surjectivity check when return type is sealed

Scala can warn when pattern match on a sealed type is not exhaustive, however can we check that a function returns all cases when the return type is sealed? For example, consider the following ADT sealed trait Foo case object Bar extends Foo case object Qux extends Foo Then function f: Foo => String...

In Haskell, why non-exhaustive patterns are not compile-time errors?

This is a follow-up of Why am I getting "Non-exhaustive patterns in function..." when I invoke my Haskell substring function? I understand that using -Wall , GHC can warn against non-exhaustive patterns. I'm wondering what's the reason behind not making it a compile-time error by default given that...