Emit – Re: Factor

One of the interesting aspects of a concatenative language like Factor is that blocks of logic can be easily extracted and easily reused since they apply logic to objects on the stack.

But, notice that we have to specify that the local variable a and b have to be put back on the stack before we can call our extracted words that make the computations.

Today, someone on the Factor Discord server asked about this very issue, wanting to have extractable pieces of logic that would effectively be operating on nested local variables, wherever they are used. Inspired by the goal of don’t repeat yourself and the convenience of extracting logic that operates on the data stack.

Specifically, they wanted to be able to take blocks of logic that operate on named variables, and extract them in a similar manner to the logic blocks that operate on the stack – offering this hypothetical syntax as the goal:

Given a quotation that we have parsed in an emit description, we can build a word to replace all these lazy variables by looking them up in the current vocabulary manifest:

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