How to concatenate strings in twig

Question

Anyone knows how to concatenate strings in twig? I want to do something like:

{{ concat('http://', app.request.host) }} 

Answer 1

This should work fine:

{{ 'http://' ~ app.request.host }} 

To add a filter - like 'trans' - in the same tag use

{{ ('http://' ~ app.request.host) | trans }} 

As Adam Elsodaney points out, you can also use string interpolation, this does require double quoted strings:

{{ "http://#{app.request.host}" }} 

Answer 2

Also a little known feature in Twig is string interpolation:

{{ "http://#{app.request.host}" }}