Using Invisibles To Opt Out of Functions In a Chain

[hostilefork]

@gchiu

One idea for using invisibles is to chain functions where you make some functions disappear from the chain if they're not needed.

This is a creative idea... and I think this sort of creativity is what makes the language fun...

However...

@gchiu

sharpen: either sharpen [sharpenf/] [nihil/]
blur: either blur [blurf/] [nihil/]
pixelise: either pixelize [pixelf/] [nihil/]

return sharpen blur pixelise data

This kind of application no longer works, as there's been a necessary casualty of scaling back what "invisibility" could do inside of a single step.

"Non-Interstitial Invisibility" was removed for good reasons that are outlined here:

Making Invisible Functions (e.g. COMMENT, ELIDE)

So to have invisibles vaporize anything, you'd need to go through a COMPOSE or REDUCE step and then EVAL the result... so not that succinct. CASCADE is a better bet here.

Though at time of writing, you can get the original intent with macros:

sharpen: macro [] [return if sharpen [sharpenf]]
blur: macro [] [return if blur [blurf]]
pixelise: macro [] [return if pizelize [pixelf]]

return sharpen blur pixelise data