Re: Factor

Factor: the language, the theory, and the practice.


Saturday, April 18, 2015


Today, I made some minor improvements to the interpolate vocabulary, which provides simple string interpolation and formatting.

We have had the ability to use named variables:

IN: scratchpad "World" "name" set
               "Hello, ${name}" interpolate
Hello, World

But now we can just as easily use stack arguments (numbered from the top of the stack):

IN: scratchpad "Mr." "Anderson"
               "Hello, ${1} ${0}" interpolate
Hello, Mr. Anderson

In any order, even repeated:

IN: scratchpad "James" "Bond"
               "${0}, ${1} ${0}" interpolate
Bond, James Bond

As well as anonymously, by order of arguments:

IN: scratchpad "Roses" "red"
               "${} are ${}" interpolate
Roses are red

And even mix named variables and stack arguments:

IN: scratchpad "Factor" "lang" set
               "cool" "${lang} is ${0}!" interpolate
Factor is cool!

Right now we simply convert objects to human-readable strings using the present vocabulary. In the future, it would be nice to support something like Python’s string format specifications, which are similar but slightly different than our printf support.