OpenEuphoria

Re: Discuss changing the behaviour of append()

• Posted by _tom (admin) Jun 13, 2014
• 3926 views

Still trying to make sense of this topic. Here is a summary of a few ideas I see in this thread.

• Is change going to happen?
• How do I describe these chagnes?

_tom

From Euphoria 1.0 Documentation from 1993:

Concatenation of Sequences:

The & operator will concatenate two sequences into a longer sequence. e.g. {1, 2, 3} & {4, 5, 6} is {1, 2, 3, 4, 5, 6}. Atoms can also be concatenated: 6.5 & 9 is {6.5, 9}. {1, 2, 3} & 4 is {1, 2, 3, 4}.

Operations on Sequences:

	i = length(s)          -- length of sequence 
	s = repeat(x, a)       -- repeat x a times 
	s2 = append(s1, x)     -- append x to end of s1 
	s2 = prepend(s1, x)    -- prepend x at beginning of s1 

Twenty years later...OpenEuphoria wants to look like:

Concatenation of Objects:

The & operator will concatenate two objects into a longer sequence. e.g. {1, 2, 3} & {4, 5, 6} is {1, 2, 3, 4, 5, 6}. Atoms can also be concatenated: 6.5 & 9 is {6.5, 9}. {1, 2, 3} & 4 is {1, 2, 3, 4}.

Operations on Objects:

	i = length(x)          -- length of object 
	s = repeat(x, a)       -- repeat x a times 
	s2 = append(x1, x)     -- append x to end of x1 
	s2 = prepend(x1, x)    -- prepend x at beginning of x1 

1. Keep things the way they were
2. Extend Euphoria

Keep Things

• change is bad
• some suble changes in program behaviour if append is changed?
• append was optimized for speed; do not sacrifice this speed
• & is a "sequence creation" operator; therefore it makes sense that you can concatenate two atoms
• append is a "sequence modifying" function; therefore it makes sense that you can not start with an atom

Extend Euphoria

• length has already been changed
• a complementary change given that length is now different
• fits the existing pattern that & already has
• promoting an atom a to a sequence {a} is a convenience that is expected because of the flexibility of Euphoria
• usability is more valuable than interpreter speed
• thinking in terms of objects is more powerful than thinking in terms of just sequences