Not sure what editor you use, but most syntax highlighters these days can mix languages: you see this e.g. in HTML <style> tags and Markdown fenced code blocks.

Not sure what editor you use, but most syntax highlighters these days can mix languages: you see this e.g. in HTML <style> tags and Markdown fenced code blocks. As for 'out of order programming', I think that TANGLE-style reordering is a lot less important with modern programming languages: they don't do one-pass compilation and so can deal with forward references. Note that most of the cross-references in Knuth's program could be replaced with function calls or constant names, rather than the semiautomatic inlining that WEB performs. I've had some success in writing literate programs in a Markdown file, with a small script to extract the code blocks into a file for execution. This seems to work fine, at least on a small scale, and is very easy to implement and then extend if needed. Edit: and by “small script” I mean: import sys code = False for line in sys.stdin.read().splitlines(): if line == '```': code = False # End block if code: print(line) # Only output block contents if line == '```md': code = True # Start block It also seems worth noting that you can get much the same result just by writing a lot of comments; this technique is mainly useful when you also want more formatting than can be reasonably squeezed into plain text. /edit