Appendix B. The TYPEs

B.1 Types available in pymdl

<ALLTYPES> of a fresh pymdl, each with its PRIMTYPE and, where the built-in type census carries one, the MDL 55 type code (octal) -- the number a compiled RSUBR sees in the left half of a type word. Generated by tools/book_gen.py; 66 types. The vector is MDL 55's own order -- element k+1 is the TYPE with code k, the built-ins first -- and the codes no TYPE is named for hold the ATOM INTERNAL, left out here.

TYPE	PRIMTYPE	era code
LOSE	WORD	0
FIX	WORD	1
FLOAT	WORD	2
CHARACTER	WORD	3
SUBR	WORD	5
FSUBR	WORD	6
UNBOUND	WORD	7
ILLEGAL	WORD	11
TIME	WORD	12
LIST	LIST	13
FORM	LIST	14
SEGMENT	LIST	15
FUNCTION	LIST	16
CLOSURE	LIST	17
LOCL	LOCL	20
FALSE	LIST	21
UVECTOR	UVECTOR	23
OBLIST	UVECTOR	24
VECTOR	VECTOR	25
CHANNEL	VECTOR	26
LOCV	LOCV	27
TAG	VECTOR	32
PROCESS	PROCESS	33
MACRO	LIST	40
TUPLE	TUPLE	42
FRAME	FRAME	45
STRING	STRING	46
ATOM	ATOM	47
LOCD	LOCD	50
BYTES	BYTES	51
ENVIRONMENT	FRAME	52
ACTIVATION	FRAME	53
ASOC	ASOC	54
LOCU	LOCU	55
LOCS	LOCS	56
LOCA	LOCA	57
TEMPLATE	TEMPLATE	61
LOCT	LOCT	62
LOCR	LOCR	63
QUICK-RSUBR	VECTOR	65
QUICK-ENTRY	VECTOR	66
WORD	WORD	70
RSUBR	VECTOR	71
CODE	UVECTOR	72
PRIMTYPE-C	WORD	73
BITS	WORD	74
STORAGE	STORAGE	75
PICTURE	STORAGE	76
LINK	ATOM	100
IHEADER	VECTOR	101
HANDLER	VECTOR	102
LOCAS	LOCAS	103
DECL	LIST	104
DISMISS	ATOM	105
RSUBR-ENTRY	VECTOR	107
SPLICE	LIST	110
PCODE	WORD	111
TYPE-W	WORD	112
TYPE-C	WORD	113
READA	FRAME	115
LOCB	LOCB	120
OFFSET	OFFSET	122
PYCODE	WORD
DATA-BASE!-LIB	VECTOR
CURSOR!-IEDIT	VECTOR
BREAK	LIST

B.2 Type behavior and representation

The following classification records the predefined types of the historical interpreter, including evaluation, application, and reading restrictions. It complements the current type census above. The type facilities and pymdl differences are explained in chapter 9; structures are covered in chapter 10.

On these two pages is a table showing each of MDL's predefined TYPEs, its primitive type if different, and various flags: S for STRUCTURED, E for EVALTYPE not QUOTE, and A for APPLICABLE.

X means that an object of that TYPE cannot be CHTYPEd to and hence cannot be READ in (if attempted, a CAN'T-CHTYPE-INTO error is usual).

B means that an object of that TYPE cannot be READ in (if attempted, a STORAGE-TYPES-DIFFER error is usual), that instead it is built by the interpreter or CHTYPEd to by a program, and that its PRINTed representation makes it look as though its TYPEPRIM were different.

% means that an object of that TYPE is PRINTed using % notation and can be READ in only that way.

TYPE	TYPEPRIM	S	E	A		comments
ACTIVATION	FRAME				X
ASOC					B	sic: only one S
ATOM
BITS	WORD
BYTES		S
CHANNEL	VECTOR	S			X
CHARACTER	WORD
CLOSURE	LIST	S		A
CODE	UVECTOR	S
DECL	LIST	S
DISMISS	ATOM					can be returned by interrupt handler
ENVIRONMENT	FRAME				B
FALSE	LIST	S
FIX	WORD			A
FLOAT	WORD
FORM	LIST	S	E
FRAME					B
FSUBR	WORD			A	X
FUNCTION	LIST	S		A
HANDLER	VECTOR	S			X
IHEADER	VECTOR	S			X	"interrupt header"
ILLEGAL	WORD				X	Garbage collector may put this on non-LEGAL? object.
INTERNAL	INTERNAL-TYPE				X	should not be seen by programs
LINK	ATOM				X	for terminal shorthand
LIST		S	E
LOCA					B	locative to TUPLE
LOCAS					B	locative to ASOC
LOCB					B	locative to BYTES
LOCD					%	locative to G/LVAL
LOCL					B	locative to LIST
LOCR					%	locative to GVAL in pure program
LOCS					B	locative to STRING
LOCT					B	locative to TEMPLATE
LOCU					B	locative to UVECTOR
LOCV					B	locative to VECTOR
LOSE	WORD					a place holder
MACRO	LIST	S		A
OBLIST	UVECTOR	S			X
OFFSET	OFFSET			A	%
PCODE	WORD				%	"pure code"
PRIMTYPE-C	WORD				%	"primtype code"
PROCESS					B
QUICK-ENTRY	VECTOR	S		A	%	an RSUBR-ENTRY that has been QCALLed and RSUBR-LINKed
QUICK-RSUBR	VECTOR	S		A	%/B	an RSUBR that has been QCALLed and RSUBR-LINKed
READA	FRAME				X	in eof slot during recursive READ via READ-TABLE
RSUBR	VECTOR	S		A	%/B	if code vector is pure/impure, respectively
RSUBR-ENTRY	VECTOR	S		A	%
SEGMENT	LIST	S	E
SPLICE	LIST	S				for returning many things via READ-TABLE
STORAGE		S				If possible, use FREEZE SUBR instead.
STRING		S
SUBR	WORD			A	X
TAG	VECTOR	S			X	for non-local GOs
TEMPLATE		S			B	Built with the TEMPLATE package; see chapter 31.
TIME	WORD					used internally to identify FRAMEs
TUPLE		S			B	vector on the control stack
TYPE-C	WORD				%	"type code"
TYPE-W	WORD				%	"type word"
UNBOUND	WORD				X	value of unassigned but bound ATOM, as seen by locatives
UVECTOR		S	E			"uniform vector"
VECTOR		S	E
WORD