Этот код:
import Data.Char (digitToInt)
myInt :: String -> Int
myInt [] = error "bad input: empty string"
myInt (x:xs)
| x == '-' = -1 * myInt xs
| otherwise = foldl convert 0 (x:xs)
where convert acc x
| x `elem` ['0'..'9'] = 10 * acc + digitToInt x
| otherwise = error ("bad input: not an int - " ++ [x])
Не удается:
Prelude> :l safeListFs.hs
[1 of 1] Compiling Main ( safeListFs.hs, interpreted )
safeListFs.hs:9:8: parse error (possibly incorrect indentation)
Failed, modules loaded: none.
Но эта версия:
import Data.Char (digitToInt)
myInt :: String -> Int
myInt [] = error "bad input: empty string"
myInt (x:xs)
| x == '-' = -1 * myInt xs
| otherwise = foldl convert 0 (x:xs)
where convert acc x
| x `elem` ['0'..'9'] = 10 * acc + digitToInt x
| otherwise = error ("bad input: not an int - " ++ [x])
нормально:
Prelude> :l safeListFs.hs
[1 of 1] Compiling Main ( safeListFs.hs, interpreted )
Ok, modules loaded: Main.
Я не могу понять, почему эти два последних отступа имеют значение.