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I am semi-new to clojure and I’m sitting with an funcool/octet problem, would this be the right forum to ask questions?


well assuming this is the right forum, I’ll ask and we’ll see what I receive : ) I’m trying to parse parts of the zip file specification using octet and a fair amount of the spec uses variable length strings. octet supports variable length strings, but if I’m reading things correctly, only if the length is a four byte int32 and immediately preceding the string data. The zip spec has plenty of instances where the you have a record and the stringlength is either an int16 or is not immediately before the data. I would like to solve this with a custom special-string* spec which would take a keyword as an argument and the keyword would point to the spec containing the length of the string.


example from zip specification:

central file header signature        4 bytes  (0x02014b50)
     file name length                2 bytes
     extra field length              2 bytes
     file comment length             2 bytes
     disk number start               2 bytes
     internal file attributes        2 bytes
     external file attributes        4 bytes
     relative offset of local header 4 bytes

     file name (variable size)
     extra field (variable size)
     file comment (variable size)
in this case I would like to have:
   :file-name-length int16
   :extra-field-length int16
   :file-comment-length int16
   :file-name (special-string* :file-name-length)


or something similar, fair chance I’m missing something as I don’t have all that much mileage with clojure


I haven’t been able to figure out how to write this custom spec and any help or pointers would be much appreciated