Week2: 4 and 5

[BertLisser]

Exercise 4

instance Arbitrary RandomIntListSmall where
arbitrary = fmap RandomIntListSmall [(elements [1..10])]

doesn't work

Couldn't match expected type `[Int]' with actual type `Gen a0'
    In the return type of a call of `sublistOf'
    In the expression: (sublistOf[1 .. 10])
    In the second argument of `fmap', namely `[(sublistOf[1 .. 10])]'

must become

arbitrary = do
                   x<-(sublistOf[1..10])
                  return (RandomIntListSmall  x)

I don't understand how your code was able to run.
But the rest and approach was good.

Good

Exercise 5

Perfect

[Oipo]

Regarding exercise 4, I am unsure where you see

instance Arbitrary RandomIntListSmall where
arbitrary = fmap RandomIntListSmall [(elements [1..10])]

As in the latest commit of the submitted Lab 2.hs file(5:41 PM, Sep 17 GMT +2) this is what is used for exercise 4:

data RandomIntListSmall = RandomIntListSmall [Int] deriving Show
instance Arbitrary RandomIntListSmall where
arbitrary = fmap RandomIntListSmall (sublistOf [1..10])

Could you check whether you have the latest code or if you've accidentally commented on the wrong group's code?

[BertLisser]

Sorry if have changed sublistOf in elements. I thought that it was a problem of sublistOf. But that was not the case.
I tested it first with:

    instance Arbitrary RandomIntListSmall where
    arbitrary = fmap RandomIntListSmall (sublistOf [1..10])

These lines are in ST2017_WG_12/submission/lab 2/Lab 2.hs

[Oipo]

That's odd. I just loaded it in ghci and it works fine. I'm using ghci 7.10.3 with quickcheck 2.10.0.1:

oipo@oipo-B85M-HD3 ~/Documents/UvA/master/Software Testing/ST2017_WG_12/submission/lab 2 $ ghci
GHCi, version 7.10.3: http://www.haskell.org/ghc/  :? for help
Prelude> :load "Lab 2.hs"
[1 of 1] Compiling Lab2             ( Lab 2.hs, interpreted )
Ok, modules loaded: Lab2.
*Lab2> exerciseFour 
"True"
+++ OK, passed 100 tests.
Success {numTests = 100, labels = [], output = "+++ OK, passed 100 tests.\n"}
*Lab2>

oipo@oipo-B85M-HD3 ~/Documents/UvA/master/Software Testing/ST2017_WG_12/submission/lab 2 $ cabal info quickcheck | grep installed
    Versions installed: 2.10.0.1

[BertLisser]

I have install a new quickcheck (2.10.0.1) and exercise 4 works. I am curious to hear from you why. I must confess that I did't know this construct.