Optimize sequence comprehension 'Head

[jklmnn]

Sequence comprehensions can be used to filter list elements. To get the first element of a specific type the current implementation looks as follows:

New_Seq := [for E in List if E.Type = Type1 => E];
First_Elem := New_Seq'Head;

The problem with that implementation is that it creates a new list where searching through the existing list would be sufficient. To optimize this particular behaviour the following expression will be optimized to only do a search until an element is found and return that element:

First_Elem := [for E in List if E.Type = Type1 => E]'Head;

[jklmnn]

The basic code generation for this feature seems to work. The generated code compiles. Both accessing the complete element and accessing a field of an element works. However arrays with scalar elements still generate broken code.