Is there a way to find if a sequence of two chars are found in a list only if they are consecutive?

I am currently working in the elm syntax. An example would be like this:

(Sequence ('a') ('b')) ('c') ['a', 'b', 'c', 'd'] . In this example, i only test if the elements 'a', 'b', 'c' are members of the list. If yes, then i partition it and obtain (['a','b','c'],['d'])

I encountered problems in the following case:

 (Sequence ('a') ('b')) ('c') ['a', 'b', 'c', 'a']

obtaining the result : (['a','b','c','a'],[])

My question is: what condition should i put such that the elements 'a' and 'b' must be consecutive avoiding the case when they are matched alone?

Solution

This answer assumes that if you have Sequence 'a' 'b' 'c' and test it against the list ['a', 'b', 'c', 'a'], you want to receive the result (['a', 'b', 'c'], ['a']) (as asked in this comment).

In pseudo-code:

Split the list into two, list1 and list2. list1 should have the same length as your sequence. Elm provides List.take and List.drop for that
Convert your sequence into a list list_sequence with a helper function
Test if list1 and list_sequence are equal
If they are, return the tuple (list1, list2)

And here is the actual Elm code: https://ellie-app.com/bjBLns4dKkra1