Week 3 Exercise 4 (First reaction)

[BertLisser]

First reaction:

Whilst the quickCheck run was successful it was slow, taking an average of 1:39, to complete 100 tests over 5 runs.

try (for example)

verboseCheckWith stdArgs { maxSize = 15 }

propIdGen = frequency [
    (60, choose(1, 3)),
    (30, choose(4, 7)),
    (9, choose(8, 20)),
    (1, choose(21, 10000000))]

Why this distribution?
I propose

(4, ...)
(2,...)
(1,...)

The sum of the frequencies doesn't need be 100.

Nice work. I continue with reading and understanding.

Important test cases are missed by excluding the empty list as argument.
See

lenGen::Gen Int
lenGen = frequency [
    (90, choose(2, 3)),
    (9, choose(4, 10)),
(1, choose(11, 50))]

I changed this into for example

lenGen::Gen Int
lenGen = frequency [
    (90, choose(0, 3))   --,
  --  (9, choose(4, 10)),
   -- (1, choose(11, 50))]

and added the line

fdg s' 0 = do return []

to fdg
and verboseCheck prop_validCnfConversion accepts al the test cases.

Very good work (=9)