How to make a function closure in Jinja / dbt

jinja_closure.sql

{# Save these macros in your dbt project /macros folder: #}

{% macro enclose(fn, env) %}
    {% set closure = namespace(fn=fn, env=env) %}
    {% do return(closure) %}
{% endmacro %}

{% macro call1(closure, x1) %}
    {% do return(closure.fn(x1, closure.env)) %}
{% endmacro %}

{% macro call2(closure, x1, x2) %}
    {% do return(closure.fn(x1, x2, closure.env)) %}
{% endmacro %}

{% macro power(x, kwargs) %}
    {% do return(x**kwargs.exponent) %}
{% endmacro %}


{# Example, within a dbt model: #}

{% set square = enclose(power, dict(exponent=2)) %}

{{ call1(square, 8) }}{# = 8**2 = 64 #}

See also: How to do partial function application in Jinja / dbt