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Partial functions in Prelude
Functions that aren't even partial
| Function
|
Witness
|
| error
|
error "x"
|
| undefined
|
undefined
|
List functions
| Function
|
Only partial for infinite lists
|
Witness
|
| maximum
|
No
|
maximum []
|
| minimum
|
No
|
minimum []
|
| head
|
No
|
head []
|
| tail
|
No
|
tail []
|
| init
|
No
|
init []
|
| last
|
No
|
last []
|
| foldl
|
Yes
|
foldl (const (const ())) () [0..]
|
| foldl'
|
Yes
|
foldl' (const (const ())) () [0..]
|
| foldl1
|
No
|
foldl1 (const (const ())) []
|
| foldl1'
|
No
|
foldl1' (const (const ())) []
|
| foldr1
|
No
|
foldr1 (const (const ())) []
|
| cycle
|
No
|
cycle []
|
| !!
|
No
|
[] !! 0
|
| filter
|
Yes
|
filter (const False) [0..]
|
| dropWhile
|
Yes
|
dropWhile (const True) [0..]
|
| length
|
Yes
|
length [0..]
|
| sum
|
Yes
|
sum [0..]
|
| product
|
Yes
|
product [0..]
|
| reverse
|
Yes
|
reverse [0..]
|
Other
| Function
|
Witness
|
| read
|
read "x" :: Int
|
| quot
|
1 `quot` 0
|
| rem
|
1 `rem` 0
|
| quotRem
|
1 `quotRem` 0
|
| div
|
1 `div` 0
|
| mod
|
1 `mod` 0
|
| divMod
|
1 `divMod` 0
|
| succ
|
succ ()
|
| pred
|
pred ()
|
| toEnum
|
toEnum 1 :: ()
|
| (^)
|
1 ^ (-1)
|
| fail
|
fail "x" :: Either () ()
|
| ... (todo)
|
Partial functions in other base libraries
Data.List
| Function
|
Only partial for infinite lists
|
Witness
|
| genericIndex
|
No
|
genericIndex [] 0
|
| genericLength
|
Yes
|
genericLength [0..] :: Integer
|
Data.Map
| Function
|
Witness
|
| (!)
|
Map.empty ! ()
|
Data.Maybe
| Function
|
Witness
|
| fromJust
|
fromJust Nothing
|
Partial functions in other Haskell Platform packages
| Function
|
Witness
|
| ... (todo)
|