It's not that there's a textual intermediate format: just a defined intermediate tree structure. Some examples are given in the nanopass framework documentation

It's not that there's a textual intermediate format: just a defined intermediate tree structure. Some examples are given in the nanopass framework documentation [0]. So it's not that the input language is processed into an intermediate format, which is printed to a string and then read by the next pass; the intermediate languages are all in various forms of trees. See also the paper on writing Chez Scheme as a nanopass system [1]. [0] https://docs.racket-lang.org/nanopass/index.html https://docs.racket-lang.org/nanopass/index.html [1] https://www.cs.indiana.edu/~dyb/pubs/commercial-nanopass.pdf https://www.cs.indiana.edu/~dyb/pubs/commercial-nanopass.pdf