CODEWITHSUNDEEP
haskellghci
schuelermine
schuelermine

Reputation: 2290

How do I prevent GHCi from "crashing" from this?

I tried running this code, and it ended up making GHCi unusable. Meaning, the command line (Windows) ended up not responding to any input and simply displaying an empty line.

Prelude> b = ["Empty", "Discrete", "Distinct", "Defiant", "Useful", "Good", 
"Imperative", "Safe", "Lawful", "Unpresidented", "Decadent", "Rich", 
"Strong", "Marvelous", "Volatile", "Obtuse", "Acute", "Revolutionary", 
"Frank", "Regular"]
Prelude> length b
20
Prelude> import Data.Char
Prelude Data.Char> a = [ map toLower x | x <- a ]
Prelude Data.Char> a

......

Upvotes: 0

Views: 122

Answers (1)

n. m. could be an AI
n. m. could be an AI

Reputation: 119847

This is fully expected and normal behaviour.

 a = [ map toLower x | x <- a ]

is a recursive definition of a, where the recursion never ends. Note a at both sides of the equals sign. GHCi is not crashing, it just runs this code for always and always, until you interrupt it by pressing Ctrl-C.

Upvotes: 4

Related Questions