Jinja2TT2 (early-stage) Jinja2 → Template Toolkit 2 (Perl) transpiler

[lucianofedericopereira]

Hi everyone,

I’ve built an experimental transpiler that converts Jinja2 templates into Perl Template Toolkit 2 (TT2). The goal is to help teams that want to reuse existing Jinja2 templates in Perl environments or migrate gradually without rewriting everything by hand.

Repository: https://github.com/lucianofedericopereira/jinja2tt2

Supported Constructs

Variables

{{ foo }}           →  [% foo %]
{{ user.name }}     →  [% user.name %]
{{ items[0] }}      →  [% items.0 %]

Filters

{{ name|upper }}              →  [% name.upper %]
{{ name|lower|trim }}         →  [% name.lower.trim %]
{{ items|join(", ") }}        →  [% items.join(', ') %]
{{ name|default("Guest") }}   →  [% (name || 'Guest') %]

Conditionals

{% if user %}          →  [% IF user %]
{% elif admin %}       →  [% ELSIF admin %]
{% else %}             →  [% ELSE %]
{% endif %}            →  [% END %]

Loops

{% for item in items %}    →  [% FOREACH item IN items %]
{{ loop.index }}           →  [% loop.count %]
{{ loop.first }}           →  [% loop.first %]
{{ loop.last }}            →  [% loop.last %]
{% endfor %}               →  [% END %]

Blocks and Macros

{% block content %}        →  [% BLOCK content %]
{% endblock %}             →  [% END %]

{% macro btn(text) %}      →  [% MACRO btn(text) BLOCK %]
{% endmacro %}             →  [% END %]

Comments

{# This is a comment #}    →  [%# This is a comment %]

Whitespace Control

{{- name -}}               →  [%- name -%]
{%- if x -%}               →  [%- IF x -%]

Other Constructs

• {% include "file.html" %} → [% INCLUDE file.html %]
• {% set x = 42 %} → [% x = 42 %]
• Ternary: {{ x if cond else y }} → [% (cond ? x : y) %]
• Boolean literals: true/false → 1/0

Filter Mapping

Jinja2	TT2 Equivalent
upper	.upper
lower	.lower
trim	.trim
first	.first
last	.last
length	.size
join	.join
reverse	.reverse
sort	.sort
escape / e	| html_entity
default	|| operator
replace	.replace

Some filters require TT2 plugins (e.g., tojson needs Template::Plugin::JSON).

Loop Variable Mapping

Jinja2	TT2
loop.index	loop.count
loop.index0	loop.index
loop.first	loop.first
loop.last	loop.last
loop.length	loop.size

Limitations

• Template inheritance ({% extends %}) requires manual adjustment for TT2's WRAPPER pattern
• Autoescape is not directly supported in TT2
• Some filters need custom TT2 plugins or vmethods
• Complex Python expressions may need review

This is still an early-stage project, so any guidance or suggestions are welcome.
Thanks for your time.