Error Messages

Prelude

The lights shine low Your moves shine lower You’re dazed- have been gooder- mouth tastes like syntactic sugar.

You wander through Civic- people, buildings, potatoes form only vague shapes Everything looks like abstracted grapes.

Hovering over these fuzzy outlines- burning starkly- Are the error messages that have haunted you, sparkly.

Through every assignment…. Every lab… Every day.. They’re there.

But as you sit down in Maccas, and dip your fries delicately in a thickshake You reflect upon how those error messages, beneath a cold, cruel exterior… Are really there to help you good code, make.

Through every assignment… Every lab… Every day… They’re there for you.

You cry to your waiter: “We’re all going to make mistakes Yet, beautiful Haskell, gives such in-depth feedback If you heed it well, you can never go wrong, hot cakes!”

You decide it’s time to go back and find every error message you’ve ever been given… It’s time to make use of that feedback.

error:
    parse error on input ‘|’

Couldn't match expected type `String -> String'
            with actual type `[Char]'
In the expression: "****"
In an equation for `****': **** = "****"

error:
    * Variable not in scope: lenth :: [Int] -> Int
    * Perhaps you meant `length' (imported from Prelude)

error:
 parse error on input ‘->’*

Couldn't match expected type `a' with actual type `[a]'
  `a' is a rigid type variable bound by
      the type signature for ****** at YUNOWORK.hs:1:9
In the pattern: x : xs
In the pattern: [x : xs]
In a case alternative: [x : xs] -> x + *** xs

error:
    Variable not in scope: y

error:
    Multiple declarations of `shadowed_function'

error:
Parse error in pattern: ***

Could not deduce (a ~ a1)
from the context (Ord a)
  bound by the type signature for
             biggerThan :: Ord a => a -> [a] -> [a]
  at brokeyo.hs:16:15-38
or from (Ord a1)
  bound by the type signature for remove :: Ord a1 => [a1] -> [a1]
  at brokeyo.hs:19:15-33
  `a' is a rigid type variable bound by
      the type signature for biggerThan :: Ord a => a -> [a] -> [a]
      at brokeyo.hs:16:15
  `a1' is a rigid type variable bound by
       the type signature for remove :: Ord a1 => [a1] -> [a1]
       at brokeyo.hs:19:15
In the second argument of `(<)', namely `y'
In the expression: x < y
In a stmt of a pattern guard for
               an equation for `remove':
  x < y

 error:
    * Variable not in scope: lisAdd :: [Int] -> Int
    * Perhaps you meant `listAdd'

    No instance for (Num [(a, Int)]) arising from a use of `helper'
    Possible fix: add an instance declaration for (Num [(a, Int)])
    In the expression: helper (x : xs) 1
    In a case alternative:
        (x : xs)
          -> helper (x : xs) 1
          where
              helper list acc
                = case list of {
                    [] -> ****
                    (x : xs) -> ... : *** }
    In the expression:
      case list of {
        [] -> ****
        (x : xs)
          -> helper (x : xs) 1
          where
              helper list acc
                = case list of {
                    [] -> ...
                    (x : xs) -> ... } }

*** Exception: Non-exhaustive patterns in function

Hint: This error only appears during runtime (when input is given)