@include std.core
@include std.mem

def Segment(nominal, str value)
    return @args // return all inputs

def Segment(String _value)
    value = _value.str() // convert from all String types
    return nominal.Segment(value)

def combine(Segment[] segments)
    @mut s = str("")     // convert "" to mutable str
    on Stack.arena(1024) // automatic use when needed
    segments.len().range().while next(@mut u64 i)
        then s = str(s+segments[i].value+" ")
    return combined

service main()
    segments = Segment[] 
    .push(Segment("I think."))
    .push(Segment("Therefore I am."))
    segments
    .combine()
    .print()

Details

In the example, freeing the arena is safely delayed until printing. All operations are also zero-cost abstractions over performant implementations at the core of the standard library. Code blocks either end or return. Furthermore:

• def functions that can fail and produce nominal values.
• service functions run safely; if a def fails, resources are cleaned up.
• nominal declares a nominal type variation.
• then is followed by the last expression of the code block.
• @mut denotes mutable variables (their values change as the program runs).
• on is automatically added as first argument - here to store string addition on a fast arena allocator.
• . member values or curries a first argument into functions.
• [] declares buffers.