Math filters return incorrect types compared to Shopify/Liquid

[ryo-morimoto]

The math filters (plus, minus, times, modulo) always return float regardless of input types. This differs from Shopify/Liquid's behavior where:

• Integer + Integer → Integer
• Float involved → Float
• String integers (e.g., '20') → treated as Integer
• String decimals (e.g., '20.0') → treated as Float

Currently, all math filters use (float) cast unconditionally, which breaks compatibility with Shopify/Liquid.

Examples

plus

Template	Expected (Shopify)	Current (php-liquid)
{{ 1 | plus:1 }}	2 (int)	2.0 (float)
{{ '1' | plus:'1.0' }}	2.0 (float)	2.0 (float) ✓

minus

Template	Expected (Shopify)	Current (php-liquid)
{{ 5 | minus:1 }}	4 (int)	4.0 (float)
{{ '4.3' | minus:'2' }}	2.3 (float)	2.3 (float) ✓

times

Template	Expected (Shopify)	Current (php-liquid)
{{ 3 | times:4 }}	12 (int)	12.0 (float)
{{ 'foo' | times:4 }}	0 (int)	0.0 (float)
{{ 0.0725 | times:100 }}	7.25 (float)	7.25 (float) ✓

modulo

Template	Expected (Shopify)	Current (php-liquid)
{{ 3 | modulo:2 }}	1 (int)	1.0 (float)

Refs

• Shopify/Liquid apply_operation: https://github.com/Shopify/liquid/blob/32b50ecafecae41b924f3e3120c6dc587efdd800/lib/liquid/standardfilters.rb#L1003-L1006
• Shopify/Liquid Utils.to_number: https://github.com/Shopify/liquid/blob/32b50ecafecae41b924f3e3120c6dc587efdd800/lib/liquid/utils.rb#L51-L66
• Shopify/Liquid test cases: https://github.com/Shopify/liquid/blob/32b50ecafecae41b924f3e3120c6dc587efdd800/test/integration/standard_filter_test.rb#L693-L743