Bare builtin names resolve as truthy; `or`/`and` and undefined comparisons diverge

[Nuhiat-Arefin]

Three related behaviors diverge from Jinja2 on templates that use bare builtin names, boolean operators, or undefined operands.

1. Bare builtin names resolve to functions in the run scope, and functions are truthy. Jinja2 does not expose filters or tests as variables, so those names are Undefined (falsy):

{{ f or divisibleby }}

Jinja2 renders empty. ginger renders 1.

2. or and and compile to any/all and return a boolean instead of the deciding operand:

{{ f or empty }}

with empty = []: Jinja2 renders [], ginger renders empty.

3. Comparisons involving undefined or null operands compare by truthiness:

{{ number != upper }}

Jinja2 renders False. ginger renders 1.

Root cause

defaultScope is seeded into the run scope (src/Text/Ginger/Run.hs:641-650); fromFunction gives functions asBoolean = True (src/Text/Ginger/GVal.hs:686-695); or/and compile to any/all (src/Text/Ginger/Parse.hs:1072-1080, src/Text/Ginger/Run/Builtins.hs:136-140); looseEquals compares null operands by truthiness (src/Text/Ginger/Run/Builtins.hs:200-209, line 208).