# Student asked me why "no implicit conversion of nil to integer" **URL:** \ **Category:** Support, Help & Resources\ **Created:** [April 10, 2024, 1:15pm UTC](https://in-thread.sonic-pi.net/t/student-asked-me-why-no-implicit-conversion-of-nil-to-integer/8767 "2024-04-10T13:15:21Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![brendanmac](https://dub1.discourse-cdn.com/flex017/user_avatar/in-thread.sonic-pi.net/brendanmac/32/2809_2.png) [@brendanmac](https://in-thread.sonic-pi.net/u/brendanmac)\ **Post date:** [April 10, 2024, 1:15pm UTC](https://in-thread.sonic-pi.net/t/student-asked-me-why-no-implicit-conversion-of-nil-to-integer/8767/1 "2024-04-10T13:15:21Z")
Hallo friends my young student and I are exploring a few different and simple ways of programming drum patterns, including arrays of numbers or of symbols. When we came to this example: ```ruby k1 = [9,0,0,0,7,0,0,5] # how loud is each sound, div by 10.0 s1 = [0,0,6,0,0,0,4,0] h1 = [0,8,0,5,0,7,0,4] h2 = [5,0,4,0,3,0,2,0] live_loop :drums98 do #stop sample :bd_zum, amp: k1.tick * 0.1 sample :sn_zome, amp: s1.look * 0.1 sample :hat_bdu, amp: h1.look * 0.1 sample :hat_gnu, amp: h2.look * 0.1 sleep 0.25 end ``` He asked if we could use a loop counter to tick through the arrays, and use k1[i] \* 0.1 (as we had in a previous working example), instead of .tick. Using live\_loop :drums98 do | i | the answer is no we can’t. The previous working example was this one: ```ruby drm = [1,0,2,0,1,0,2,1] cym = [0,1,0,2,0,1,0,2] live_loop :drums1 do stop 8.times do |i| #loop counter sample :drum_bass_hard if drm[i] == 1 sample :sn_dolf if drm[i] == 2 sample :hat_bdu if cym[i] == 1 sample :hat_gnu if cym[i] == 2 sleep 0.25 end end ``` I realise this example polls the array and then applies a conditional, and the example above that is polling the array for the actual value itself. Again, revealing my n00bosity - where is the nil coming from, and why can’t we index through the array values in the first example. I tried k[1].to\_i without success. Many thanks for your continued support Brendan ---
**Author:** ![brendanmac](https://dub1.discourse-cdn.com/flex017/user_avatar/in-thread.sonic-pi.net/brendanmac/32/2809_2.png) [@brendanmac](https://in-thread.sonic-pi.net/u/brendanmac)\ **Post date:** [April 10, 2024, 1:21pm UTC](https://in-thread.sonic-pi.net/t/student-asked-me-why-no-implicit-conversion-of-nil-to-integer/8767/2 "2024-04-10T13:21:21Z")
Yet this works fine. It reveals my basic lack of understanding of how the loop counter works - if it’s at the head of the loop it behaves differenter (yes, it’s a word :D) to when it’s assigned to a nested loop: ```ruby k1 = [9,0,0,0,7,0,0,5] s1 = [0,0,6,0,0,0,4,0] h1 = [0,8,0,5,0,7,0,4] h2 = [5,0,4,0,3,0,2,0] live_loop :drums28 do #stop 8.times do |i| sample :bd_zum, amp: k1[i] * 0.1 sample :sn_zome, amp: s1[i] * 0.1 sample :hat_bdu, amp: h1[i] * 0.1 sample :hat_gnu, amp: h2[i] * 0.1 sleep 0.25 end end ``` Hey ho ---
**Author:** ![brendanmac](https://dub1.discourse-cdn.com/flex017/user_avatar/in-thread.sonic-pi.net/brendanmac/32/2809_2.png) [@brendanmac](https://in-thread.sonic-pi.net/u/brendanmac)\ **Post date:** [April 10, 2024, 3:45pm UTC](https://in-thread.sonic-pi.net/t/student-asked-me-why-no-implicit-conversion-of-nil-to-integer/8767/3 "2024-04-10T15:45:39Z")
I am slowly coming to the realisation (the correct one, I believe) that any time I post a question here it is not about Sonic Pi specifically, it is more about programming in general, particularly using Ruby. If I spend 2hrs a day coding, about 25 - 50 % of that time is learning about Ruby. And having great fun too. Sonic Pi doesn’t present me with any barriers or problems - they stem from my ‘lack’ of programming skills (although I did teach Supercollider for a few years at uni). So I have decided to begin learning Ruby formally (and the experts here can say if that is a good or bad idea), either online or locally . Wish me luck 😉 ---
**Author:** ![emlyn](https://dub1.discourse-cdn.com/flex017/user_avatar/in-thread.sonic-pi.net/emlyn/32/1460_2.png) [@emlyn](https://in-thread.sonic-pi.net/u/emlyn)\ **Post date:** [April 14, 2024, 12:15am UTC](https://in-thread.sonic-pi.net/t/student-asked-me-why-no-implicit-conversion-of-nil-to-integer/8767/4 "2024-04-14T00:15:02Z")
I’m not sure what the issue is, but I suspect it might be to do with indexing outside of the array. When you use the `array[x]` notation (as opposed to `array.tick`), it will return a `nil` value when the index is out of range, instead of looping back to the start. You can prevent this by converting the arrays to rings, then indexing will always loop back to the start, e.g.: `k1 = [9,0,0,0,7,0,0,5].ring` or `k1 = ring(9,0,0,0,7,0,0,5)`. ---
**Author:** ![Davids-Music-Lab](https://dub1.discourse-cdn.com/flex017/user_avatar/in-thread.sonic-pi.net/davids-music-lab/32/512_2.png) [@Davids-Music-Lab](https://in-thread.sonic-pi.net/u/Davids-Music-Lab)\ **Post date:** [April 15, 2024, 1:25pm UTC](https://in-thread.sonic-pi.net/t/student-asked-me-why-no-implicit-conversion-of-nil-to-integer/8767/5 "2024-04-15T13:25:16Z")
The reason this works with the `8.times` loop is that `i` only exists within that loop and is set to zero every time the live\_loop repeats, so you don’t go out of bounds. Making k1, s1, etc rings instead of lists would avoid that problem. ---
**Author:** ![brendanmac](https://dub1.discourse-cdn.com/flex017/user_avatar/in-thread.sonic-pi.net/brendanmac/32/2809_2.png) [@brendanmac](https://in-thread.sonic-pi.net/u/brendanmac)\ **Post date:** [April 15, 2024, 3:41pm UTC](https://in-thread.sonic-pi.net/t/student-asked-me-why-no-implicit-conversion-of-nil-to-integer/8767/6 "2024-04-15T15:41:58Z")
Thanks both for the confirmation