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| author | Kaz Kylheku <kaz@kylheku.com> | 2015-09-08 07:01:42 -0700 |
|---|---|---|
| committer | Kaz Kylheku <kaz@kylheku.com> | 2015-09-08 07:01:42 -0700 |
| commit | 94d029b0f24756b84a94ce2b3f8fd5739166b0c5 (patch) | |
| tree | 8b12005298141f11225387bd75a3e38898f4e627 /txr.1 | |
| parent | f72fa1121f2571aba9f16f95d58d8e915965d765 (diff) | |
| download | txr-94d029b0f24756b84a94ce2b3f8fd5739166b0c5.tar.gz txr-94d029b0f24756b84a94ce2b3f8fd5739166b0c5.tar.bz2 txr-94d029b0f24756b84a94ce2b3f8fd5739166b0c5.zip | |
New functions, subtypep and typep.
* eval.c (eval_init): Register subtypep and typep.
* eval.h (list_s): Existing variable declared.
* lib.c (atom_s, integer_s, number_s, sequence_s, string_s):
new symbol variables.
(subtypep, typep): New functions.
(obj_init): Initialize new symbol variables.
* lib.c (atom_s, integer_s, number_s, sequence_s, string_s):
Declared.
* txr.1: Documented type hierarchy and the new functions.
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 144 |
1 files changed, 144 insertions, 0 deletions
@@ -12968,6 +12968,106 @@ is a symbol which names a special operator, otherwise it returns .codn nil . .SS* Object Type And Equivalence + +In \*(TL, objects obey the following type hierarchy. In this type hierarchy, +the internal nodes denote abstract types: no object is an instance of +an abstract type: + +.cblk + t ----+--- <cobj types> ---+--- hash + | | + | +--- stream + | | + | +--- random-state + | | + | . + | +... <others> + | + +--- <structures> + | + +--- sequence ---+--- string ---+--- str + | | | + | | +--- lstr + | | | + | | +--- lit + | | + | +--- list ---+--- null + | | | + | | +--- cons + | | | + | | +--- lcons + | | + | +--- vec + | + +--- number ---+--- float + | | + | +--- integer ---+--- fixnum + | | + | +--- bignum + | + +--- sym + | + +--- env + | + +--- pkg + | + +--- fun +.cble + +In addition to the above hierarchy, the following relationships also exist: + +.cblk + t ---+--- atom --- <any type other than cons> --- nil + | + +--- cons ---+--- lcons --- nil + | + +--- nil + + sym --- null +.cble + +That is to say, the types are exhaustively partitioned into atoms and conses; +an object is either a +.code cons +or else it isn't, in which case it is the abstract +type +.codn atom . + +The +.code cons +type is odd in that it is both an abstract type, +serving as a supertype for the type +.code lcons +and it is also a concrete type in that regular conses are of +this type. + +The type +.code nil +is an abstract type which is empty. That is to say, no object is of +type +.codn nil . +This type is considered the abstract subtype of every other type, +including itself. + +The type +.code nil +is not to be confused with the type +.code null +which is the type of the +.code nil +symbol. + +Lastly, because the type of +.code nil +is the type +.code null +and +.code nil +is also a symbol, the +.codn null +type is a subtype of +.codn sym . + .coNP Function @ typeof .synb .mets (typeof << value ) @@ -13023,6 +13123,50 @@ A bignum integer: arbitrary precision integer that is heap-allocated. There are additional kinds of objects, such as streams. +.coNP Function @ subtypep +.synb +.mets (subtypep < left-type-symbol << right-type-symbol ) +.syne +.desc +The +.code subtypep +function tests whether +.meta left-type-symbol +and +.meta right-type-symbol +name a pair of types, such that the left type is a subtype of the right +type. + +Each type is a subtype of itself. Most other type relationships can be inferred +from the type hierarchy diagrams given in the introduction to this section. + +In addition, there are inheritance relationships among structures. If +.meta left-type-symbol +and +.meta right-type-symbol +both name structure types, then +.code subtypep +yields true if the types are the same struct type, or if the right +type is a direct or indirect supertype of the left. + +.coNP Function @ typep +.synb +.mets (typep < object << type-symbol ) +.syne +.desc +The +.code typep +function tests whether the type of +.meta object +is a subtype of the type named by +.meta type-symbol . + +The following equivalence holds: + +.cblk + (typep a b) --> (subtypep (typeof a) b) +.cble + .coNP Function @ identity .synb .mets (identity << value ) |