Documentation

Calculate size of an instance of IsSequence as the sum:

• of the size of all the elements
• plus the size of the array constructors (1 byte every 255 elements plus one final byte)

Encode an instance of IsSequence, as an array

Decode an instance of IsSequence, as an array

Encode an instance of IsMap, as a list of (Key,Value) tuples

Decode an instance of IsMap, as a list of (Key,Value) tuples

Sequences are defined as Arrays:

Array v = A0 | A1 v (Array v) | A2 v v (Array v) ... | A255 ... (Array v)

In practice, this means that the sequence is encoded as a sequence of blocks of up to 255 elements, with every block preceded by the count of the elements in the block and a final 0-length block.

Lists are defined as:

List a ≡ Nil | Cons a (List a)

In practice, this means that the list elements will be prefixed with a 1 bit and followed by a final 0 bit.

The AsList/AsArray wrappers can be used to serialise sequences as Lists or Arrays.

Let's see some examples.

>>> flatBits $ AsList [True,True,True]
"1111110"

So we have Cons True (11) repeated three times, followed by a final Nil (0).

The list encoding is the default one for lists so AsList is in this case unnecessary:

>>> flatBits $ [True,True,True]
"1111110"

We can force a list to be encoded as an Array with AsArray:

>>> flatBits $ AsArray [True,True,True]
"00000011 11100000 000"

We have the initial block with a count of 3 (3 == 00000011) followed by the elements True True True (111) and then the final block of 0 elements ("00000 000").

>>> flatBits $ [AsArray [True,True,True]]
"10000001 11110000 00000"

>>> flatBits $ (True,True,True,AsArray $ replicate 7 True)
"11100000 11111111 11000000 00"

>>> flatBits $ AsArray ([]::[()])
"00000000"

>>> flatBits $ AsList ([]::[()])
"0"

>>> tst (AsList [11::Word8,22,33])
(True,28,[133,197,164,32])

>>> tst (AsSet (Data.Set.fromList [11::Word8,22,33]))
(True,28,[133,197,164,32])

>>> tst [AsArray [1..3], AsArray [4..8]]
(True,99,[129,129,2,3,0,65,66,2,131,3,132,0,0])

>>> tst $ [AsArray [(1::Word8)..3], AsArray [4..8]]
(True,99,[129,128,129,1,128,65,65,1,65,129,194,0,0])

>>> tst $ [AsArray [(1::Int)..3]]
(True,42,[129,129,2,3,0,0]) 

Sets are saved as lists of values.

>>> tstBits $ AsSet (Data.Set.fromList ([False,True,False]::[Bool]))
(True,5,"10110") 

Maps are saved as lists of (key,value) tuples.

>>> tst (AsMap (Data.Map.fromList ([]::[(Word8,())])))
(True,1,[0])

>>> tst (AsMap (Data.Map.fromList [(3::Word,9::Word)]))
(True,18,[129,132,128])