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163 lines
4.0 KiB
Markdown
163 lines
4.0 KiB
Markdown
section 2eA, packing
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====================
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### `++cue`
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Unpack atom to noun
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++ cue :: unpack atom to noun
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~/ %cue
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|= a=@
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^- *
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=+ b=0
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=+ m=`(map ,@ ,*)`~
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=< q
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|- ^- [p=@ q=* r=_m]
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?: =(0 (cut 0 [b 1] a))
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=+ c=(rub +(b) a)
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[+(p.c) q.c (~(put by m) b q.c)]
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=+ c=(add 2 b)
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?: =(0 (cut 0 [+(b) 1] a))
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=+ u=$(b c)
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=+ v=$(b (add p.u c), m r.u)
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=+ w=[q.u q.v]
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[(add 2 (add p.u p.v)) w (~(put by r.v) b w)]
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=+ d=(rub c a)
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[(add 2 p.d) (need (~(get by m) q.d)) m]
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::
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Produces a noun unpacked from atom `a`. The inverse of jam.
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`a` is an [atom]().
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~zod/try=> (cue 12)
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1
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~zod/try=> (cue 817)
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[1 1]
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~zod/try=> (cue 4.657)
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[1 2]
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~zod/try=> (cue 39.689)
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[0 19]
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------------------------------------------------------------------------
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### `++jam`
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++ jam :: pack
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~/ %jam
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|= a=*
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^- @
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=+ b=0
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=+ m=`(map ,* ,@)`~
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=< q
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|- ^- [p=@ q=@ r=_m]
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=+ c=(~(get by m) a)
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?~ c
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=> .(m (~(put by m) a b))
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?: ?=(@ a)
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=+ d=(mat a)
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[(add 1 p.d) (lsh 0 1 q.d) m]
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=> .(b (add 2 b))
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=+ d=$(a -.a)
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=+ e=$(a +.a, b (add b p.d), m r.d)
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[(add 2 (add p.d p.e)) (mix 1 (lsh 0 2 (cat 0 q.d q.e))) r.e]
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?: ?&(?=(@ a) (lte (met 0 a) (met 0 u.c)))
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=+ d=(mat a)
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[(add 1 p.d) (lsh 0 1 q.d) m]
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=+ d=(mat u.c)
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[(add 2 p.d) (mix 3 (lsh 0 2 q.d)) m]
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::
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Produces an atom unpacked from noun `a`. The inverse of cue.
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`a` is a [noun]().
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~zod/try=> (jam 1)
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12
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~zod/try=> (jam [1 1])
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817
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~zod/try=> (jam [1 2])
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4.657
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~zod/try=> (jam [~ u=19])
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39.689
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------------------------------------------------------------------------
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### `++mat`
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Length-encode
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++ mat :: length-encode
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~/ %mat
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|= a=@
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^- [p=@ q=@]
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?: =(0 a)
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[1 1]
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=+ b=(met 0 a)
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=+ c=(met 0 b)
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:- (add (add c c) b)
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(cat 0 (bex c) (mix (end 0 (dec c) b) (lsh 0 (dec c) a)))
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Produces a cell whose tail `q` is atom `a` with a bit representation of
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its length prepended to it (as the least significant bits). The head `p`
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is the length of `q` in bits.
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`a` is an atom.
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~zod/try=> (mat 0xaaa)
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[p=20 q=699.024]
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~zod/try=> (met 0 q:(mat 0xaaa))
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20
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~zod/try=> `@ub`q:(mat 0xaaa)
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0b1010.1010.1010.1001.0000
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~zod/try=> =a =-(~&(- -) `@ub`0xaaa)
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0b1010.1010.1010
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~zod/try=> =b =-(~&(- -) `@ub`(xeb a))
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0b1100
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~zod/try=> =b =-(~&(- -) `@ub`(met 0 a))
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0b1100
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~zod/try=> =c =-(~&(- -) (xeb b))
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4
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~zod/try=> [`@ub`a `@ub`(end 0 (dec c) b) `@ub`(bex c)]
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[0b1010.1010.1010 0b100 0b1.0000]
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------------------------------------------------------------------------
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### `++rub`
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Length-decode
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++ rub :: length-decode
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~/ %rub
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|= [a=@ b=@]
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^- [p=@ q=@]
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=+ ^= c
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=+ [c=0 m=(met 0 b)]
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|- ?< (gth c m)
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?. =(0 (cut 0 [(add a c) 1] b))
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c
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$(c +(c))
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?: =(0 c)
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[1 0]
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=+ d=(add a +(c))
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=+ e=(add (bex (dec c)) (cut 0 [d (dec c)] b))
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[(add (add c c) e) (cut 0 [(add d (dec c)) e] b)]
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The inverse of `++mat`. Accepts a cell of index `a` and a bitstring `b`
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and produces the cell whose tail `q` is the decoded atom at index `a`
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and whose head is the length of the encoded atom `q`, by which the
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offset `a` is advanced. Only used internally as a helper cue.
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`a` is an atom.
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`b` is a bitstring as an atom.
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~zod/try=> `@ub`(jam 0xaaa)
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0b1.0101.0101.0101.0010.0000
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~zod/try=> (rub 1 0b1.0101.0101.0101.0010.0000)
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[p=20 q=2.730]
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~zod/try=> `@ux`q:(rub 1 0b1.0101.0101.0101.0010.0000)
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0xaaa
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------------------------------------------------------------------------
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