2. The Eight Myths of Erlang Performance

2 The Eight Myths of Erlang Performance

Some truths seem to live on well beyond their best-before date, perhaps because "information" spreads faster from person-to-person than a single release note that says, for example, that funs have become faster.

This section tries to kill the old truths (or semi-truths) that have become myths.

2.1 Myth: Funs are Slow

Funs used to be very slow, slower than apply/3. Originally, funs were implemented using nothing more than compiler trickery, ordinary tuples, apply/3, and a great deal of ingenuity.

But that is history. Funs was given its own data type in R6B and was further optimized in R7B. Now the cost for a fun call falls roughly between the cost for a call to a local function and apply/3.

2.2 Myth: List Comprehensions are Slow

List comprehensions used to be im