Lambda the Ultimate

I am going to initiate a marginally on-topic discussion, Ehud - please correct me if it is not on-topic at all.

Let's say I have a well-defined binary file format¹, consisting of structural elements of different granularity ranging from unsigned ints to tagged blocks to sequences to complete files, and I want to express this structural elements in my PL, covering at least reading the file, analyzing/transforming it at the level of structural elements (as opposed to bits/bytes), and writing it back. An example would be optimizing Flash file for size, while preserving its functionality.

Additional points for:

1. Compile-time checking to some extent (yes, it's unfair)
2. Natural support of tagged blocks - e.g., block with tag 22 must have this type, while block with tag 42 must have that type (explicit "switch" does not count)
3. Natural support of bit-fields (explicit bit-shifting does not count)
4. Ditto with variable bit-field length (Byte n; BitField[n] x; BitField[x] y)
5. Symmetric serialization/deserialization specification (ideally this should be completely defined by the structure of type)

Well, I realize that this sound too much like a DSL for describing file formats, but the question is - which of general-purpose PLs come sufficiently close to this (very informal) specification? Is dependent typing the most natural solution for variable length of fields and tagged blocks?

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¹If you are familiar with SWF you may think of this hypothetical format as SWF (if not, think RIFF, MIDI, etc.).