What is the preferred syntax for initializing a dict: curly brace literals {} or the dict() function?

Curly braces. Passing keyword arguments into dict(), though it works beautifully in a lot of scenarios, can only initialize a map if the keys are valid Python identifiers.

This works:

a = {'import': 'trade', 1: 7.8}

a = dict({'import': 'trade', 1: 7.8})

This won’t work:

a = dict(import="trade", 1=7.8)

It will result in the following error:

    a = dict(import="trade", 1=7.8)
             ^
SyntaxError: invalid syntax