re: Daily Challenge #103 - Simple Symbols VIEW POST


simple Haskell solution:

verify :: String -> Bool
verify [] = True
verify ('+':x:'+':xs)
    | isLetter x = verify $ '+':xs
verify (x:xs)
    | isLetter x = False
    | otherwise = verify xs

Whoa, I was comming with something that involved using an indexedMap but your solution is very clever. Thanks for sharing your awesome answer!

Also, isn't isLetter part of Data.Char? Or no need to import that to use the isLetter function?


yes, that function is from Data.Char, I omitted the import together with the module header.


I took your solution and simplified it:

verify :: String -> Bool
verify [] = True
verify ('+':x:'+':xs) = verify $ '+':xs
verify ('+':xs) = verify xs
verify ('=':xs) = verify xs
verify (_) = False

Also note that nothing in the question indicates the characters other than = and + can only be letters. Your version would accept 1 even though 1 is a character and it is not surrounded by +s.


This solution assumes that the only other character is =. No idea if you can assume this

The string will be composed of + and = symbols with several characters between them.

If I'm reading this correctly, it means that the characters are categorized into three categories:

  1. +
  2. =
  3. Other

So any character other than + and = must be surrounded by +s - which is exactly what my version checks.

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