Problem 42: Coded triangle numbers. Rewrote the original python code and wrote a new Haskell code.
Problem 43: Sub-string divisibility. Six seconds in Haskell.
Problem 41: Pandigital Prime. Brute force with Haskell in half a second. You can skip all permutations other than 4 and 7 digits because all of them can be divisible by 3.
Problem 40: Champernowne's constant. Now I understood infinite list and foldr/foldl in Haskell.
Problem 39: Integer right triangles. Simple brute force in Haskell. 20 seconds.
Problem 38: Pandigital multiples. Brute force in Haskell. 10 seconds.
Problem 37: Truncatable primes. I am still struggling with Haskell. 15 seconds in Haskell.
Problem 36: Double base palindromes. One second in Haskell.
Problem 34: Digit factorials. Done with Haskell.
Problem 35: Circular primes. One minutes with compiled Haskell. Too slow.
Problem 32: Pandigital Products. Much better than my original code in Python. Both in Python and Haskell.