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1.1 ! root 1: .ND ! 2: .nr LL 75n ! 3: .nr LT 80n ! 4: .rm CF ! 5: .ds LH PEARL Documentation ! 6: .ds CH Update ! 7: .ds RH Page % ! 8: .po 1.50i ! 9: .ls 1 ! 10: .hy 14 ! 11: .LP ! 12: .bp 76 ! 13: .DS C ! 14: .LG ! 15: \fBUpdate of Changes ! 16: Through ! 17: PEARL 3.9 ! 18: April 1983\fR ! 19: .SM ! 20: .DE ! 21: .SH ! 22: 1. Introduction ! 23: .PP ! 24: This appendix describes the changes that have been made to PEARL since ! 25: the original manual was produced. ! 26: It is designed to parallel the sections of the manual so that the ! 27: original index can be used to find changes. ! 28: .PP ! 29: PEARL is now distributed with Franz Lisp (starting with Opus 38.58). ! 30: The earliest version of PEARL distributed (with 38.58) was PEARL 3.6. ! 31: The current update corresponds to version 3.9 and is being distributed ! 32: with the Franz Opus 38.69 available with 4.2 BSD Unix. ! 33: The current major and minor version numbers for PEARL are stored in ! 34: the special variables \fIpearlmajorversion\fR and \fIpearlminorversion\fR ! 35: respectively. ! 36: .PP ! 37: With the change in mail protocols and addition of new machines at ! 38: Berkeley, the form of addresses for bugs and suggestions have been ! 39: simplified. ! 40: Bugs, suggestions or queries should be sent to ! 41: \fIPearl\-Bugs@Berkeley\fR or \fIucbvax!pearl\-bugs\fR. ! 42: .SH ! 43: 2. Running PEARL ! 44: .PP ! 45: PEARL is currently only maintained under Franz Lisp. ! 46: The current version could be moved back to UCI Lisp (or to other ! 47: Lisps) fairly easily but has not been for lack of need. ! 48: Lisp Machine Lisp is the most likely Lisp that PEARL will be moved ! 49: to next but it has not been done, mostly because of conflicts in the ! 50: use of the colon character and lack of access to a Lisp Machine. ! 51: .SH ! 52: 2.1 Under Franz Lisp ! 53: .PP ! 54: Since PEARL is now part of Franz Lisp, it should be available as ! 55: \fI/usr/ucb/pearl\fR or wherever you find \fIlisp\fR on your system. ! 56: .PP ! 57: The \fI.start.pearl\fR and \fI.init.pearl\fR files are actually ! 58: called \fIstart.prl\fR and \fIinit.prl\fR and may optionally be ! 59: prefixed with a dot "." and/or suffixed with either ".o" or ".l" just ! 60: as in Franz. ! 61: The use of the dot prefix and of the ".o" or ".l" is preferred ! 62: and fastest. ! 63: Thus PEARL will read the first file found in the following ! 64: sequence: \fI.init.prl.o\fR, \fI.init.prl.l\fR, \fI.init.prl\fR, ! 65: \fIinit.prl.o\fR, \fIinit.prl.l\fR, or \fIinit.prl\fR and similarly ! 66: for \fIstart.prl\fR. ! 67: Franz's special variable \fI$ldprint\fR is lambda-bound to \fInil\fR during ! 68: the reading of these two files to disable the printing of ! 69: "[load .init.prl]". ! 70: .SH ! 71: 5. Accessing Slots of Structures ! 72: .PP ! 73: Doing a "\fIpath \fBput\fR" on a slot containing a variable will ! 74: not set the variable. ! 75: Rather it replaces the variable with the value provided. ! 76: .SH ! 77: 10. Printing Structures, Symbols and Other PEARL Objects ! 78: .PP ! 79: The various printing functions still exist but all call a single ! 80: formatting function with various options controlled by special atoms. ! 81: The principle functions are \fBallform\fR which does the building of a ! 82: printable list form for internal PEARL structures and \fBallprint\fR ! 83: which calls \fIallform\fR. ! 84: \fIAllform\fR uses the following global variables to determine what ! 85: form to build: ! 86: .IP 1. ! 87: \fB*abbrevprint*\fR -- a non-\fInil\fR value causes abbreviations ! 88: to be used whenever possible for any structure except the top level ! 89: structure passed to a print function. ! 90: Abbreviations are described at the end of this section. ! 91: The new functions \fBabbrevform\fR and \fBabbrevprint\fR ! 92: lambda-bind this to \fIt\fR and then call \fIallform\fR. ! 93: \fIfullform\fR binds this to \fInil\fR. ! 94: .IP 2. ! 95: \fB*fullprint*\fR -- a non-\fInil\fR value causes complete information ! 96: including hooks and predicates to be given when present. ! 97: \fIFullform\fR (and thus \fIfullprint\fR) lambda-binds this to \fIt\fR ! 98: and calls \fIallform\fR. ! 99: \fIAbbrevform\fR binds this to \fInil\fR. ! 100: .LP ! 101: \fIValform\fR lambda-binds both to \fInil\fR. ! 102: The default value of both is are also \fInil\fR, so that the default action of ! 103: \fIallform\fR when used by itself will be like \fIvalform\fR unless these ! 104: special variables are changed. ! 105: All the default print functions automatically use \fIallprint\fR so that ! 106: they can all be changed by changes to the default values of ! 107: \fI*abbrevprint*\fR and \fI*fullprint*\fR. ! 108: .LP ! 109: Two other special atoms which affect the behavior of all the printing ! 110: functions are: ! 111: .IP 3. ! 112: \fB*uniqueprint*\fR -- a non-\fInil\fR value causes a structure which is ! 113: encountered more than once during the same top-level call to a ! 114: print function to be translated into exactly the same cons-cells. ! 115: This saves on cons-cells and also makes it possible for the \fI\-\-form\fR ! 116: functions to handle circular structures, although \fIsprint\fR and thus ! 117: the \fI\-\-print\fR functions cannot handle the result. ! 118: Since most people seldom have duplications within a structure, ! 119: the default is \fInil\fR (off). ! 120: The assoc\-list of already translated structures is stored in the ! 121: special atom \fB*uniqueprintlist*\fR. ! 122: .IP 4. ! 123: \fB*quiet*\fR -- a non-\fInil\fR value disables all printing by any of ! 124: PEARL's print functions, providing an easy way to disable printing ! 125: all at once. ! 126: There is also a function called \fBquiet\fR which behaves like ! 127: \fIprogn\fR, except that it lambda-binds \fI*quiet*\fR to \fIt\fR ! 128: during the evaluation of its arguments, providing a local island ! 129: of "quiet". ! 130: .PP ! 131: The standard print functions are designed to handle any Lisp structure. ! 132: Thus, they spend a significant amount of time determining what kind of ! 133: object they have been passed. ! 134: For situations in which you know exactly what type of object you want ! 135: printed, the functions ! 136: \fBstructureform/structureprint\fR, \fBsymbolform/symbolprint\fR, ! 137: and \fBstreamform/streamprint\fR are provided. ! 138: They assume you know what you are doing and do not ensure that ! 139: you give them the right type of value. ! 140: .PP ! 141: Adapting PEARL to fit an improvement in Franz, the atoms ! 142: \fIshowstack-printer\fR and \fItrace-printer\fR are bound to ! 143: the functions \fBpearlshowstackprintfn\fR and \fBpearltraceprintfn\fR. ! 144: \fBNote\fR the addition of "pearl" to the beginning of these. ! 145: The name of \fIbreakprintfn\fR was also changed to ! 146: \fBpearlbreakprintfn\fR but it is not currently lambda-bindable. ! 147: .SH ! 148: 10.1. Abbreviations ! 149: .PP ! 150: As people build larger deeper structures it becomes useful to have ! 151: some of them abbreviated during printing if they are internal to the ! 152: structure being printed. ! 153: When an individual (including default instance) structure is created, ! 154: an abbreviation atom is stored in it. ! 155: This abbreviation is chosen as follows: ! 156: .IP 1. ! 157: If the option in \fIcreate\fR of having a structure automatically ! 158: stored in an atom is used, then that atom is the one used as an ! 159: abbreviation. ! 160: Thus the structure created by \fI(create individual x Pete)\fR will ! 161: be given the abbreviation \fIPete\fR. ! 162: .IP 2. ! 163: If that option is not used, then default instances will be ! 164: given the abbreviation \fIi:x\fR (where x is the structure type name) ! 165: and individuals at the top level will be given a name \fInewsym\fR-ed ! 166: from the name of their type. ! 167: Thus \fI(create base x)\fR will make a default instance abbreviated ! 168: \fIi:x\fR and the first structure created with \fI(create individual x)\fR ! 169: will be abbreviated \fIx0\fR. ! 170: .IP 3. ! 171: \fIScopy\fR and related functions that create new structures from old ! 172: ones \fIgensym\fR the new structure's abbreviation from that of the ! 173: old structure. ! 174: .SH ! 175: 11. Error Messages, Bugs, and Error Handling Abilities ! 176: .PP ! 177: Bugs, complaints and suggestions of useful features (to be added to ! 178: the current list of 30 or so things on the wish list) should be ! 179: mailed by electronic mail to \fBPearl\-Bugs@Berkeley\fR or ! 180: \fBucbvax!pearl\-bugs\fR. ! 181: .SH ! 182: 12. Short-Circuiting and Redirecting Create Using !, $ and Atoms ! 183: .PP ! 184: If an atom is encountered where a value-description was expected in ! 185: any type of slot, and it is bound to a value of the right type, ! 186: its value is inserted into the slot. ! 187: For \fIsymbols\fR, this is done if the atom is not a symbol name. ! 188: For \fIstructures\fR, the atom must evaluate to a structure. ! 189: For \fILisp\fR slots, it must simply be bound. ! 190: For \fIsetof\fR slots, its value is checked for being of the appropriate ! 191: type, including depth of nesting. ! 192: .PP ! 193: Note also that a change in the internal representation has made it possible ! 194: to allow \fBeven atoms\fR in slots of type \fIlisp\fR. ! 195: .SH ! 196: 13. More Flexible Hash Selection ! 197: .PP ! 198: Because we have never gotten around to adding fetch functions to take ! 199: advantage of colon and colon-colon hashing and these two methods ! 200: really are not useful in normal fetching, they are currently ignored. ! 201: .PP ! 202: For situations in which you wish to create an expanded structure and ! 203: add new hashing marks to an old slot (rather than replace them), ! 204: preceding new hash marks with a plus ("+") will cause the old ! 205: hashing information to be copied before processing the new hashing. ! 206: .PP ! 207: Thus, the sequence ! 208: .DS ! 209: (cb x (* a int)) ! 210: (ce x y (a ^)) ! 211: (ce x z (+ : a ^)) ! 212: (ce x w (: + a ^)) ; anomalous use of + ! 213: .DE ! 214: will result in: ! 215: .DS ! 216: * hashing in x, ! 217: no hashing in y, ! 218: both * and : hashing in z, and ! 219: only * hashing in w (because of misplacement of +). ! 220: .DE ! 221: .PP ! 222: Several new hashing methods have been added to PEARL. ! 223: .PP ! 224: A hashing mechanism using the label \fB***\fR has been added called ! 225: "triple-star hashing". ! 226: If slots are labeled with *** and \fBall\fR slots so marked are filled ! 227: with useful values, then the item is hashed under the type of structure ! 228: plus the values of all these slots. ! 229: During fetching, this is considered the most useful (that is, ! 230: specific) hash method. ! 231: .PP ! 232: A hashing mechanism using the label \fB&&\fR has been added called ! 233: "hash focusing". ! 234: It is designed for people using a data base all of ! 235: whose entries are of the same type (not required, just common ! 236: for this application) and enables the contents of a single slot ! 237: to be used to better discriminate them. ! 238: Examples of such structures are "planfors", inference rules, ! 239: or almost any other such extremely-common binary predicates. ! 240: If a slot labeled && is found when inserting into the database then ! 241: the item is hashed as if it were the item in the slot so labeled. ! 242: At fetching time, && is considered less useful than *** or ** ! 243: and more useful than * or nothing. ! 244: .PP ! 245: This differs from & (hash aliasing) in that hash focusing ! 246: affects how a structure itself is inserted and fetched, while ! 247: & simply affects how structures containing this type of ! 248: structure are treated. ! 249: For example, suppose the unique numbers of A, B, and C ! 250: respectively are 1, 2, and 3. ! 251: C is a symbol. ! 252: A has one slot X with * and && hashing. ! 253: B has one slot Y of type symbol with * hashing. ! 254: Then a structure like (A (X (B (Y C)))) will be indexed the ! 255: following ways and \fIfetcheverywhere\fR (see below) will find ! 256: it in the following order: the && method will be used first ! 257: which uses the 2 and 3 from B and its C, (ignoring the 1 of A), ! 258: and also simply 2 from B; ! 259: the * on A uses the type of B thus using 1 and 2; ! 260: it is also looked for under the 1 of A without using 2 or 3. ! 261: If B had an & in its slot then the * on A is affected by & on B thus ! 262: using 1 and 3 (ignoring the 2 of B). ! 263: .PP ! 264: Thus, if you consider A, B, and C to be three levels of information ! 265: in the structure, an item can be hashed under any combination of two ! 266: of those levels. ! 267: The normal * method uses levels 1 and 2, ! 268: the aliasing & method ignores level 2 and uses levels 1 and 3, ! 269: and the new focussing && method ignores level 1 and uses levels 2 and 3. ! 270: In addition, the item can be put under 1, 2 or 3 individually by ! 271: various combinations of marks (1 = none, 2 = :, 3 = :+&). ! 272: The only unavailable combination of the three is all of them. ! 273: .SH ! 274: 16. Attaching Hooks to Structures (If-Added Demons) ! 275: .PP ! 276: Slot hooks are now always inherited and added to, rather than replaced. ! 277: If the hooks and predicates of a slot are preceded by \fBinstead\fR ! 278: then inheriting does not happen and hooks and predicates are replaced. ! 279: .PP ! 280: The atoms for path hooks were misnamed in such a way that you could not ! 281: use \fIhidden\fR and \fIvisible\fR. ! 282: Instead of \fI*rungethooks*\fR, and other \fI*run...hooks*\fR forms, ! 283: they are now \fB*rungetpathhooks*\fR and other \fB*run...pathhooks*\fR. ! 284: Note that they must be called as (\fIXXX\fRpath ...) and not ! 285: (path\ \fIXXX\fR ...) when used with \fIhidden\fR and \fIvisible\fR. ! 286: .SH ! 287: 17. Creating and Manipulating Multiple Data Bases ! 288: .PP ! 289: The function \fIsetdbsize\fR can now be done at any time and ! 290: will remove all current databases before changing the size, ! 291: warn the user (if \fI*warn*\fR is set) and recreate \fI*maindb*\fR ! 292: with the special variable \fI*db*\fR pointing to it. ! 293: .PP ! 294: The function \fIcleardb\fR is now a local database clearer ! 295: and its effects do not extend up the database hierarchy. ! 296: .SH ! 297: 19. Creating Expanded Subtypes of Previously Defined Objects ! 298: .PP ! 299: Hashing in old slots inherited by new expanded structures can now be ! 300: added to by preceding the new hash marks with plus ("+"). ! 301: See section 13 above. ! 302: .PP ! 303: The name of an old slot inherited by a new expanded structure may be ! 304: changed by following the new name by the old slotname preceded with ! 305: an equal sign. ! 306: Thus for example: ! 307: .DS ! 308: pearl> (create base X (A struct)) ! 309: (X (A (nilstruct))) ! 310: pearl> (create expanded X Y (B =A) (C .....)) ! 311: (Y (B (nilstruct)) (C .....))) ! 312: .DE ! 313: Note that there may not be a space between the equal sign and the slot ! 314: name since \fI=\fR is a read macro which expands \fI=A\fR into ! 315: \fI(*slot* A)\fR but leaves a single space-surrounded equal sign alone. ! 316: The actual effect is to add another name to the slot so that it can be ! 317: later referenced with either name. ! 318: .SH ! 319: 20. Fetching Expanded Structures ! 320: .PP ! 321: A fetching function called \fBfetcheverywhere\fR exists which gathers ! 322: \fBall\fR the buckets the object could have been hashed into and ! 323: builds a stream out of all of them (potentially five buckets). ! 324: There is currently no "expanded" counterpart, since it has the potential ! 325: of returning \fI5 times the-depth-of-the-hierarchy\fR buckets. ! 326: .SH ! 327: 21.2 The Matching Process ! 328: .PP ! 329: During matching, if an unbound global variable is set and ! 330: the match later fails, the value is restored to \fI*pearlunbound*\fR. ! 331: The names of variables that are set are saved in the special variable ! 332: \fB*globalsavestack*\fR. ! 333: .PP ! 334: Formerly, there was only one match function which was used by both ! 335: \fIstandardfetch\fR and \fIexpandedfetch\fR and which therefore would ! 336: match two structures if they were hierarchically related. ! 337: This is really inappropriate for the standard fetching, so ! 338: there are now two regular match functions, \fIstandardmatch\fR and ! 339: \fIbasicmatch\fR, which will only match two structures of the same type, ! 340: and two expanded match functions, \fIstandardexpandedmatch\fR and ! 341: \fIbasicexpandedmatch\fR, which will match two structures which are ! 342: related hierarchically (one above the other) on the slots they have ! 343: in common. ! 344: Streams built by \fIstandardfetch\fR use the regular versions and ! 345: and streams built by \fIexpandedfetch\fR use the expanded versions. ! 346: .PP ! 347: There are now two functions \fBmemmatch\fR and \fBmemstrequal\fR which ! 348: are like \fImemq\fR except that they use \fImatch\fR and \fIstrequal\fR ! 349: respectively instead of \fIeq\fR. ! 350: .PP ! 351: As of version 3.8, PEARL will now do \fBunification\fR of variables in ! 352: pattern matching. ! 353: To turn it on, call the function \fBuseunification\fR. ! 354: (The current implementation precludes turning it off once it is on but ! 355: this may be remedied in later versions if we can figure out what it ! 356: means to stop unifying.) ! 357: .SH ! 358: 26. Looping and Copying Functions ! 359: .PP ! 360: The function \fIscopy\fR no longer deletes bound adjunct variables. ! 361: .PP ! 362: The standard Franz function \fIcopy\fR is no longer redefined since ! 363: the standard version now avoids the copying of hunks. ! 364: .PP ! 365: The functions \fIscopy\fR and \fIpatternize\fR are now exprs rather ! 366: than macros. ! 367: .PP ! 368: The new function \fBvarreplace\fR permanently "freezes" the values ! 369: of slots containing bound variables by replacing all bound variables ! 370: in an item with their values. ! 371: .PP ! 372: A variation on \fIscopy\fR called \fBintscopy\fR ("internal scopy") ! 373: is designed to do the copying as if the copied item were internal to ! 374: another outer item, thus sharing its local and block variables. ! 375: Its arguments are the item to be copied and the outer item in whose ! 376: scopy the copying should be done. ! 377: .SH ! 378: 29. Appendix of UCI Lisp functions added to Franz PEARL ! 379: .PP ! 380: The definitions of \fIde\fR, \fIdf\fR, \fIdm\fR, \fIdrm\fR and \fIdsm\fR ! 381: have been modified so that if the special variable \fB*savedefs*\fR ! 382: is \fInil\fR then old definitions of functions are not saved. ! 383: This is especially useful in compiling (and as a result, assembly ! 384: and loading) since it will speed them up quite a bit. ! 385: This also disables the saving of the name of the file that the ! 386: definition was in. ! 387: The variable \fI*savedefs*\fR is normally \fIt\fR which causes these ! 388: macros to act as before, saving the definition, etc. ! 389: If \fI*savedefs*\fR is \fInil\fR, then they simply expand into the ! 390: appropriate \fIdefun\fR or \fIsetsyntax\fR. ! 391: The following lines should be included in a file to have this effect ! 392: only at compile time: ! 393: .DS ! 394: (eval-when (compile) ! 395: (declare (special *savedefs*)) ! 396: (setq *savedefs* nil)) ! 397: .DE ! 398: .LP ! 399: If you also want to permanently disable this feature in a lisp, that ! 400: loads \fIucisubset.l\fR, simply put a \fI(setq *savedefs* nil)\fR ! 401: in your \fI.lisprc\fR file AFTER the loading of \fIucisubset.l\fR. ! 402: .PP ! 403: The function \fIremove\fR is no longer made equivalent to Franz's ! 404: \fIdelete\fR so that Franz's \fIremove\fR can be used. ! 405: The functions \fInth\fR, \fIpush\fR and \fIpop\fR are no longer ! 406: defined by PEARL, since the new Franz versions are better. ! 407: (UCI Lisp users note: This switches the arguments to \fIpush\fR.) ! 408: .SH ! 409: 32. Index of Global Variables and Functions With Their Arguments ! 410: .PP ! 411: All special variables in PEARL are now defined with \fIdefvar\fR so ! 412: that \fIfasl\fR'ing in \fIpearl.o\fR at compile time will automatically ! 413: declare them special again. ! 414: .PP ! 415: All the exprs whose names were of the form \fIXXXX1\fR where ! 416: \fIXXXX\fR was the name of a lexpr which was a principle function ! 417: of PEARL were eliminated (i.e., absorbed by the other form). ! 418: .SH ! 419: 34. Compiling Lisp+PEARL Files. ! 420: .PP ! 421: To compile a file of mixed Lisp and PEARL functions with \fIliszt\fR, ! 422: you must first load in the function definitions and special ! 423: declarations of PEARL by loading the object code. ! 424: This is the file \fIpearl.o\fR which is normally kept in the ! 425: \fI/usr/lib/lisp\fR directory and will found automatically by ! 426: \fIload\fR. ! 427: .PP ! 428: Thus, the following should normally be included at the ! 429: beginning of a PEARL file you wish to compile: ! 430: .DS ! 431: (eval-when (compile) ! 432: (declare (special defmacro-for-compiling)) ! 433: (setq defmacro-for-compiling t) ! 434: (load 'pearl.o)) ! 435: (declare (macros t)) ! 436: .DE ! 437: .rm CF ! 438: .rm LH ! 439: .rm CH ! 440: .rm RH ! 441: .bp ! 442: .DS C ! 443: .LG ! 444: \fBUpdate of Changes ! 445: Through ! 446: PEARL 3.9 ! 447: April 1983 ! 448: .sp 1 ! 449: Table of Contents\fR ! 450: .SM ! 451: .DE ! 452: .DS L ! 453: 1. Introduction \ka76 ! 454: 2. Running PEARL \h'|\nau'76 ! 455: 2.1. Under Franz Lisp \h'|\nau'76 ! 456: 5. Accessing Slots of Structures \h'|\nau'76 ! 457: 10. Printing Structures, Symbols and Other PEARL Objects \h'|\nau'76 ! 458: 10.1. Abbreviations \h'|\nau'77 ! 459: 11. Error Messages, Bugs, and Error Handling Abilities \h'|\nau'78 ! 460: 12. Short-Circuiting and Redirecting \fICreate\fR Using !, $ and Atoms \h'|\nau'78 ! 461: 13. More Flexible Hash Selection \h'|\nau'78 ! 462: 16. Attaching Hooks to Structures (If-Added Demons) \h'|\nau'79 ! 463: 17. Creating and Manipulating Multiple Data Bases \h'|\nau'80 ! 464: 19. Creating Expanded Subtypes of Previously Defined Objects \h'|\nau'80 ! 465: 20. Fetching Expanded Structures \h'|\nau'80 ! 466: 21.2 The Matching Process \h'|\nau'80 ! 467: 26. Looping and Copying Functions \h'|\nau'81 ! 468: 29. Appendix of UCI Lisp functions added to Franz PEARL \h'|\nau'81 ! 469: 32. Index of Global Variables and Functions With Their Arguments \h'|\nau'81 ! 470: 34. Compiling Lisp+PEARL Files \h'|\nau'82 ! 471: .DE
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