Line of code not working as expected

i have a line of code which doesn’t work as i expect it too:

parentspermission x y = if x && y == False then print(“no”) else print (“yes”)

when i run parentspermission False False in ghci it gives me “yes” instead of “no” as it should be when false && false is false

this may not be worth mentioning but i am a beginner to haskell ive had some experience in python before and i am against using ai to learn haskell, i want to do it the old school way

a little addition is that when i ran parentspermission True False i got “no” as expected but when i ran parentspermission False True i somehow got “yes”

Check the precedences of (&&)

and (==)

. Neither function is magical in the language.

my understanding of this is the order i place && and ==, i would have usually placed a singlar equal sign after x && y but this isnt possible as a single equal sign is used to define functions.

The fix was to put x && y in parenthesis like so, (x && y) == False.

Noting that you are new to Haskell, you do not need ( )

around the "no"

and "yes"

values. To apply a function f :: a -> b

to x :: a

, you write f x

. Accordingly, you can write print "no"

.

Also, here, if you want Haskell code to be presented nicely, you can put it between ‘fences’ (each on their own lines) before and after the code ~~~haskell

(opening fence) and ~~~

(closing fence). For example:

parentspermission :: Bool -> Bool -> IO ()
parentspermission x y = if (x && y) == False then print “no” else print “yes”

A second also: print "no"

is equivalent to putStrLn (show "no")

. As "no"

is a String

, it may be that you do not actually want to output show "no"

but simply "no"

. That is because:

> show "no" == "\"no\""
True

(where \"

is an escaped double quote character in a Haskell string).

I’d also add to this that I’d probably usually write if not (x && y) then ... else ...

instead of (x && y) == False

in the conditional.

Edit: Also, welcome to Haskell

Building on @slow-dive 's suggestion, there is a helpful (non-AI) tool named hlint

:

which can help you learn by thinking through its suggestions.

For example, if you put your code in a module:

module MyModule
  ( parentspermission
  ) where

parentspermission :: Bool -> Bool -> IO ()
parentspermission x y = if (x && y) == False then print ("no") else print ("yes")

and command hlint MyModule

, it offers up (but in colour):

MyModule.hs:6:28-44: Suggestion: Redundant ==
Found:
  (x && y) == False
Perhaps:
  not (x && y)

MyModule.hs:6:57-62: Warning: Redundant bracket
Found:
  ("no")
Perhaps:
  "no"

MyModule.hs:6:75-81: Warning: Redundant bracket
Found:
  ("yes")
Perhaps:
  "yes"

3 hints

Thx i will check this out