Currying in CSS

This CSS snippet demonstrates a technique similar to currying, leveraging CSS custom properties (variables) for deferred calculations. The key observation is that mathematical operations within CSS variables aren't evaluated until used within a calc() function.

The example shows how custom properties --padding-S and --padding-L define calculations based on --padding. These calculations are not performed immediately. They remain as unevaluated expressions until referenced inside a calc() function, as seen in the .module--large rule. Only then does the browser perform the calculation.

This is analogous to currying in functional programming where a function returns another function, delaying the final computation until all arguments are provided. Here, the initial CSS variable assignment is like defining the initial function, and the calc() function acts as the final function call, providing the necessary context for evaluation.

The Utopia example with --fluid-max-negative and --fluid-min-negative uses the same principle. The complex calculations are defined upfront as CSS variables and only evaluated when used within a calc() function elsewhere in the stylesheet. This improves code readability and maintainability by separating the calculation definition from its application. The calculations are "curried" – the final result isn't computed until the variable is used in a context that triggers evaluation.

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