ghc/interpreter/output.c

   1
   2 /* --------------------------------------------------------------------------
   3  * Unparse expressions and types - for use in error messages, type checker
   4  * and for debugging.
   5  *
   6  * Hugs 98 is Copyright (c) Mark P Jones, Alastair Reid and the Yale
   7  * Haskell Group 1994-99, and is distributed as Open Source software
   8  * under the Artistic License; see the file "Artistic" that is included
   9  * in the distribution for details.
  10  *
  11  * $RCSfile: output.c,v $
  12  * $Revision: 1.5 $
  13  * $Date: 1999/04/27 10:06:57 $
  14  * ------------------------------------------------------------------------*/
  15
  16 #include "prelude.h"
  17 #include "storage.h"
  18 #include "connect.h"
  19 #include "errors.h"
  20 #include <ctype.h>
  21
  22 #define DEPTH_LIMIT     15
  23
  24 /* --------------------------------------------------------------------------
  25  * Local function prototypes:
  26  * ------------------------------------------------------------------------*/
  27
  28 static Void local put            Args((Int,Cell));
  29 static Void local putFlds        Args((Cell,List));
  30 static Void local putComp        Args((Cell,List));
  31 static Void local putQual        Args((Cell));
  32 static Bool local isDictVal      Args((Cell));
  33 static Cell local maySkipDict    Args((Cell));
  34 static Void local putAp          Args((Int,Cell));
  35 static Void local putOverInfix   Args((Int,Text,Syntax,Cell));
  36 static Void local putInfix       Args((Int,Text,Syntax,Cell,Cell));
  37 static Void local putSimpleAp    Args((Cell,Int));
  38 static Void local putTuple       Args((Int,Cell));
  39 static Int  local unusedTups     Args((Int,Cell));
  40 static Void local unlexOp        Args((Text));
  41
  42 static Void local putSigType     Args((Cell));
  43 static Void local putContext     Args((List,List,Int));
  44 static Void local putPred        Args((Cell,Int));
  45 static Void local putType        Args((Cell,Int,Int));
  46 static Void local putTyVar       Args((Int));
  47 static Bool local putTupleType   Args((Cell,Int));
  48 static Void local putApType      Args((Type,Int,Int));
  49
  50 static Void local putKind        Args((Kind));
  51 static Void local putKinds       Args((Kinds));
  52
  53 /* --------------------------------------------------------------------------
  54  * Basic output routines:
  55  * ------------------------------------------------------------------------*/
  56
  57 FILE *outputStream;                    /* current output stream            */
  58 Int  outColumn = 0;                    /* current output column number     */
  59
  60 #define OPEN(b)    if (b) putChr('(');
  61 #define CLOSE(b)   if (b) putChr(')');
  62
  63 Void putChr(c)                         /* print single character           */
  64 Int c; {
  65     Putc(c,outputStream);
  66     outColumn++;
  67 }
  68
  69 Void putStr(s)                        /* print string                     */
  70 String s; {
  71     for (; *s; s++) {
  72         Putc(*s,outputStream);
  73         outColumn++;
  74     }
  75 }
  76
  77 Void putInt(n)                        /* print integer                    */
  78 Int n; {
  79     static char intBuf[16];
  80     sprintf(intBuf,"%d",n);
  81     putStr(intBuf);
  82 }
  83
  84 Void putPtr(p)                        /* print pointer                    */
  85 Ptr p; {
  86     static char intBuf[16];
  87     sprintf(intBuf,"%p",p);
  88     putStr(intBuf);
  89 }
  90
  91 /* --------------------------------------------------------------------------
  92  * Precedence values (See Haskell 1.3 report, p.12):
  93  * ------------------------------------------------------------------------*/
  94
  95 #define ALWAYS      FUN_PREC           /* Always use parens (unless atomic)*/
  96                                        /* User defined operators have prec */
  97                                        /* in the range MIN_PREC..MAX_PREC  */
  98 #define ARROW_PREC  MAX_PREC           /* for printing -> in type exprs    */
  99 #define COCO_PREC   (MIN_PREC-1)       /* :: is left assoc, low precedence */
 100 #define COND_PREC   (MIN_PREC-2)       /* conditional expressions          */
 101 #define WHERE_PREC  (MIN_PREC-3)       /* where expressions                */
 102 #define LAM_PREC    (MIN_PREC-4)       /* lambda abstraction               */
 103 #define NEVER       LAM_PREC           /* Never use parentheses            */
 104
 105
 106 /* --------------------------------------------------------------------------
 107  * Print an expression (used to display context of type errors):
 108  * ------------------------------------------------------------------------*/
 109
 110 static Int putDepth = 0;               /* limits depth of printing DBG     */
 111
 112 static Void local put(d,e)             /* print expression e in context of */
 113 Int  d;                                /* operator of precedence d         */
 114 Cell e; {
 115     List xs;
 116
 117     if (putDepth>DEPTH_LIMIT) {
 118         putStr("...");
 119         return;
 120     }
 121     else
 122         putDepth++;
 123
 124     switch (whatIs(e)) {
 125         case FINLIST    : putChr('[');
 126                           xs = snd(e);
 127                           if (nonNull(xs)) {
 128                               put(NEVER,hd(xs));
 129                               while (nonNull(xs=tl(xs))) {
 130                                   putChr(',');
 131                                   put(NEVER,hd(xs));
 132                               }
 133                           }
 134                           putChr(']');
 135                           break;
 136
 137         case AP         : putAp(d,e);
 138                           break;
 139
 140         case NAME       : unlexVar(name(e).text);
 141                           break;
 142
 143         case VARIDCELL  :
 144         case VAROPCELL  :
 145         case DICTVAR    :
 146         case CONIDCELL  :
 147         case CONOPCELL  : unlexVar(textOf(e));
 148                           break;
 149
 150 #if TREX
 151         case RECSEL     : putChr('#');
 152                           unlexVar(extText(snd(e)));
 153                           break;
 154 #endif
 155
 156         case FREECELL   : putStr("{free!}");
 157                           break;
 158
 159         case TUPLE      : putTuple(tupleOf(e),e);
 160                           break;
 161
 162         case WILDCARD   : putChr('_');
 163                           break;
 164
 165         case ASPAT      : put(NEVER,fst(snd(e)));
 166                           putChr('@');
 167                           put(ALWAYS,snd(snd(e)));
 168                           break;
 169
 170         case LAZYPAT    : putChr('~');
 171                           put(ALWAYS,snd(e));
 172                           break;
 173
 174         case DOCOMP     : putStr("do {...}");
 175                           break;
 176
 177         case COMP       : putComp(fst(snd(e)),snd(snd(e)));
 178                           break;
 179
 180         case MONADCOMP  : putComp(fst(snd(snd(e))),snd(snd(snd(e))));
 181                           break;
 182
 183         case CHARCELL   : unlexCharConst(charOf(e));
 184                           break;
 185
 186         case INTCELL    : {   Int i = intOf(e);
 187                               if (i<0 && d>=UMINUS_PREC) putChr('(');
 188                               putInt(i);
 189                               if (i<0 && d>=UMINUS_PREC) putChr(')');
 190                           }
 191                           break;
 192
 193         case FLOATCELL  : {   Float f = floatOf(e);
 194                               if (f<0 && d>=UMINUS_PREC) putChr('(');
 195                               putStr(floatToString(f));
 196                               if (f<0 && d>=UMINUS_PREC) putChr(')');
 197                           }
 198                           break;
 199
 200         case STRCELL    : unlexStrConst(textOf(e));
 201                           break;
 202
 203         case LETREC     : OPEN(d>WHERE_PREC);
 204 #if DEBUG_CODE
 205                           putStr("let {");
 206                           put(NEVER,fst(snd(e)));
 207                           putStr("} in ");
 208 #else
 209                           putStr("let {...} in ");
 210 #endif
 211                           put(WHERE_PREC+1,snd(snd(e)));
 212                           CLOSE(d>WHERE_PREC);
 213                           break;
 214
 215         case COND       : OPEN(d>COND_PREC);
 216                           putStr("if ");
 217                           put(COND_PREC+1,fst3(snd(e)));
 218                           putStr(" then ");
 219                           put(COND_PREC+1,snd3(snd(e)));
 220                           putStr(" else ");
 221                           put(COND_PREC+1,thd3(snd(e)));
 222                           CLOSE(d>COND_PREC);
 223                           break;
 224
 225         case LAMBDA     : xs = fst(snd(e));
 226                           if (whatIs(xs)==BIGLAM)
 227                               xs = snd(snd(xs));
 228                           while (nonNull(xs) && isDictVal(hd(xs)))
 229                               xs = tl(xs);
 230                           if (isNull(xs)) {
 231                               put(d,snd(snd(snd(e))));
 232                               break;
 233                           }
 234                           OPEN(d>LAM_PREC);
 235                           putChr('\\');
 236                           if (nonNull(xs)) {
 237                               put(ALWAYS,hd(xs));
 238                               while (nonNull(xs=tl(xs))) {
 239                                   putChr(' ');
 240                                   put(ALWAYS,hd(xs));
 241                               }
 242                           }
 243                           putStr(" -> ");
 244                           put(LAM_PREC,snd(snd(snd(e))));
 245                           CLOSE(d>LAM_PREC);
 246                           break;
 247
 248         case ESIGN      : OPEN(d>COCO_PREC);
 249                           put(COCO_PREC,fst(snd(e)));
 250                           putStr(" :: ");
 251                           putSigType(snd(snd(e)));
 252                           CLOSE(d>COCO_PREC);
 253                           break;
 254
 255         case BIGLAM     : put(d,snd(snd(e)));
 256                           break;
 257
 258         case CASE       : putStr("case ");
 259                           put(NEVER,fst(snd(e)));
 260 #if DEBUG_CODE
 261                           putStr(" of {");
 262                           put(NEVER,snd(snd(e)));
 263                           putChr('}');
 264 #else
 265                           putStr(" of {...}");
 266 #endif
 267                           break;
 268
 269         case CONFLDS    : putFlds(fst(snd(e)),snd(snd(e)));
 270                           break;
 271
 272         case UPDFLDS    : putFlds(fst3(snd(e)),thd3(snd(e)));
 273                           break;
 274
 275         default         : /*internal("put");*/
 276                           putChr('$');
 277                           putInt(e);
 278                           break;
 279     }
 280     putDepth--;
 281 }
 282
 283 static Void local putFlds(exp,fs)       /* Output exp using labelled fields*/
 284 Cell exp;
 285 List fs; {
 286     put(ALWAYS,exp);
 287     putChr('{');
 288     for (; nonNull(fs); fs=tl(fs)) {
 289         Cell v = hd(fs);
 290         if (isVar(v))
 291             put(NEVER,v);
 292         else {
 293             Cell f = fst(v);
 294             Cell e = snd(v);
 295             Text t = isName(f) ? name(f).text :
 296                      isVar(f)  ? textOf(f)    : inventText();
 297             Text s = isName(e) ? name(e).text :
 298                      isVar(e)  ? textOf(e)    : inventText();
 299
 300             put(NEVER,f);
 301             if (haskell98 || s!=t) {
 302                 putStr(" = ");
 303                 put(NEVER,e);
 304             }
 305         }
 306         if (nonNull(tl(fs)))
 307             putStr(", ");
 308     }
 309     putChr('}');
 310 }
 311
 312 static Void local putComp(e,qs)         /* print comprehension             */
 313 Cell e;
 314 List qs; {
 315     putStr("[ ");
 316     put(NEVER,e);
 317     if (nonNull(qs)) {
 318         putStr(" | ");
 319         putQual(hd(qs));
 320         while (nonNull(qs=tl(qs))) {
 321             putStr(", ");
 322             putQual(hd(qs));
 323         }
 324     }
 325     putStr(" ]");
 326 }
 327
 328 static Void local putQual(q)            /* print list comp qualifier       */
 329 Cell q; {
 330     switch (whatIs(q)) {
 331         case BOOLQUAL : put(NEVER,snd(q));
 332                         return;
 333
 334         case QWHERE   : putStr("let {...}");
 335                         return;
 336
 337         case FROMQUAL : put(ALWAYS,fst(snd(q)));
 338                         putStr("<-");
 339                         put(NEVER,snd(snd(q)));
 340                         return;
 341     }
 342 }
 343
 344 static Bool local isDictVal(e)          /* Look for dictionary value       */
 345 Cell e; {
 346 #if !DEBUG_CODE
 347     Cell h = getHead(e);
 348     switch (whatIs(h)) {
 349         case DICTVAR : return TRUE;
 350         case NAME    : return isDfun(h);
 351     }
 352 #endif
 353     return FALSE;
 354 }
 355
 356 static Cell local maySkipDict(e)        /* descend function application,   */
 357 Cell e; {                               /* ignoring dict aps               */
 358     while (isAp(e) && isDictVal(arg(e)))
 359         e = fun(e);
 360     return e;
 361 }
 362
 363 static Void local putAp(d,e)            /* print application (args>=1)     */
 364 Int  d;
 365 Cell e; {
 366     Cell   h;
 367     Text   t;
 368     Syntax sy;
 369     Int    args = 0;
 370
 371     for (h=e; isAp(h); h=fun(h))        /* find head of expression, looking*/
 372         if (!isDictVal(arg(h)))         /* for dictionary arguments        */
 373             args++;
 374
 375     if (args==0) {                      /* Special case when *all* args    */
 376         put(d,h);                       /* are dictionary values           */
 377         return;
 378     }
 379
 380     switch (whatIs(h)) {
 381 #if NPLUSK
 382         case ADDPAT     : if (args==1)
 383                               putInfix(d,textPlus,syntaxOf(namePlus),
 384                                          arg(e),mkInt(intValOf(fun(e))));
 385                           else
 386                               putStr("ADDPAT");
 387                           return;
 388 #endif
 389
 390         case TUPLE      : OPEN(args>tupleOf(h) && d>=FUN_PREC);
 391                           putTuple(tupleOf(h),e);
 392                           CLOSE(args>tupleOf(h) && d>=FUN_PREC);
 393                           return;
 394
 395         case NAME       : if (args==1 &&
 396                               ((h==nameFromInt     && isInt(arg(e)))    ||
 397                                (h==nameFromDouble  && isFloat(arg(e))))) {
 398                               put(d,arg(e));
 399                               return;
 400                           }
 401                           t  = name(h).text;
 402                           sy = syntaxOf(h);
 403                           break;
 404
 405         case VARIDCELL  :
 406         case VAROPCELL  :
 407         case DICTVAR    :
 408         case CONIDCELL  :
 409         case CONOPCELL  : sy = defaultSyntax(t = textOf(h));
 410                           break;
 411
 412 #if TREX
 413         case EXT        : if (args==2) {
 414                               String punc = "(";
 415                               do {
 416                                   putStr(punc);
 417                                   punc = ", ";
 418                                   putStr(textToStr(extText(h)));
 419                                   putStr("=");
 420                                   put(NEVER,extField(e));
 421                                   args = 0;
 422                                   e    = extRow(e);
 423                                   for (h=e; isAp(h); h=fun(h))
 424                                       if (!isDictVal(arg(h)))
 425                                           args++;
 426                               } while (isExt(h) && args==2);
 427                               if (e!=nameNoRec) {
 428                                   putStr(" | ");
 429                                   put(NEVER,e);
 430                               }
 431                               putChr(')');
 432                               return;
 433                           }
 434                           else if (args<2)
 435                               internal("putExt");
 436                           else
 437                               args-=2;
 438                           break;
 439 #endif
 440
 441         default         : sy = APPLIC;
 442                           break;
 443     }
 444
 445     e = maySkipDict(e);
 446
 447     if (sy==APPLIC) {                   /* print simple application        */
 448         OPEN(d>=FUN_PREC);
 449         putSimpleAp(e,args);
 450         CLOSE(d>=FUN_PREC);
 451         return;
 452     }
 453     else if (args==1) {                 /* print section of the form (e+)  */
 454         putChr('(');
 455         put(FUN_PREC-1,arg(e));
 456         putChr(' ');
 457         unlexOp(t);
 458         putChr(')');
 459     }
 460     else if (args==2)                  /* infix expr of the form e1 + e2   */
 461         putInfix(d,t,sy,arg(maySkipDict(fun(e))),arg(e));
 462     else {                             /* o/w (e1 + e2) e3 ... en   (n>=3) */
 463         OPEN(d>=FUN_PREC);
 464         putOverInfix(args,t,sy,e);
 465         CLOSE(d>=FUN_PREC);
 466     }
 467 }
 468
 469 static Void local putOverInfix(args,t,sy,e)
 470 Int    args;                           /* infix applied to >= 3 arguments  */
 471 Text   t;
 472 Syntax sy;
 473 Cell   e; {
 474     if (args>2) {
 475         putOverInfix(args-1,t,sy,maySkipDict(fun(e)));
 476         putChr(' ');
 477         put(FUN_PREC,arg(e));
 478     }
 479     else
 480         putInfix(ALWAYS,t,sy,arg(maySkipDict(fun(e))),arg(e));
 481 }
 482
 483 static Void local putInfix(d,t,sy,e,f)  /* print infix expression          */
 484 Int    d;
 485 Text   t;                               /* Infix operator symbol           */
 486 Syntax sy;                              /* with name t, syntax s           */
 487 Cell   e, f; {                          /* Left and right operands         */
 488     Syntax a = assocOf(sy);
 489     Int    p = precOf(sy);
 490
 491     OPEN(d>p);
 492     put((a==LEFT_ASS ? p : 1+p), e);
 493     putChr(' ');
 494     unlexOp(t);
 495     putChr(' ');
 496     put((a==RIGHT_ASS ? p : 1+p), f);
 497     CLOSE(d>p);
 498 }
 499
 500 static Void local putSimpleAp(e,n)      /* print application e0 e1 ... en  */
 501 Cell e;
 502 Int  n; {
 503     if (n>0) {
 504         putSimpleAp(maySkipDict(fun(e)),n-1);
 505         putChr(' ');
 506         put(FUN_PREC,arg(e));
 507     }
 508     else
 509         put(FUN_PREC,e);
 510 }
 511
 512 static Void local putTuple(ts,e)        /* Print tuple expression, allowing*/
 513 Int  ts;                                /* for possibility of either too   */
 514 Cell e; {                               /* few or too many args to constr  */
 515     Int i;
 516     putChr('(');
 517     if ((i=unusedTups(ts,e))>0) {
 518         while (--i>0)
 519             putChr(',');
 520         putChr(')');
 521     }
 522 }
 523
 524 static Int local unusedTups(ts,e)       /* print first part of tuple expr  */
 525 Int  ts;                                /* returning number of constructor */
 526 Cell e; {                               /* args not yet printed ...        */
 527     if (isAp(e)) {
 528         if ((ts=unusedTups(ts,fun(e))-1)>=0) {
 529             put(NEVER,arg(e));
 530             putChr(ts>0?',':')');
 531         }
 532         else {
 533             putChr(' ');
 534             put(FUN_PREC,arg(e));
 535         }
 536     }
 537     return ts;
 538 }
 539
 540 Void unlexVar(t)                       /* print text as a variable name    */
 541 Text t; {                              /* operator symbols must be enclosed*/
 542     String s = textToStr(t);           /* in parentheses... except [] ...  */
 543
 544     if ((isascii((int)(s[0])) && isalpha((int)(s[0])))
 545        || s[0]=='_' || s[0]=='[' || s[0]=='(')
 546         putStr(s);
 547     else {
 548         putChr('(');
 549         putStr(s);
 550         putChr(')');
 551     }
 552 }
 553
 554 static Void local unlexOp(t)           /* print text as operator name      */
 555 Text t; {                              /* alpha numeric symbols must be    */
 556     String s = textToStr(t);           /* enclosed by backquotes           */
 557
 558     if (isascii((int)(s[0])) && isalpha((int)(s[0]))) {
 559         putChr('`');
 560         putStr(s);
 561         putChr('`');
 562     }
 563     else
 564         putStr(s);
 565 }
 566
 567 Void unlexCharConst(c)
 568 Cell c; {
 569     putChr('\'');
 570     putStr(unlexChar(c,'\''));
 571     putChr('\'');
 572 }
 573
 574 Void unlexStrConst(t)
 575 Text t; {
 576     String s            = textToStr(t);
 577     static Char SO      = 14;          /* ASCII code for '\SO'             */
 578     Bool   lastWasSO    = FALSE;
 579     Bool   lastWasDigit = FALSE;
 580     Bool   lastWasEsc   = FALSE;
 581
 582     putChr('\"');
 583     for (; *s; s++) {
 584         String ch = unlexChar(*s,'\"');
 585         Char   c  = ' ';
 586
 587         if ((lastWasSO && *ch=='H') ||
 588                 (lastWasEsc && lastWasDigit
 589                  && isascii((int)(*ch)) && isdigit((int)(*ch))))
 590             putStr("\\&");
 591
 592         lastWasEsc   = (*ch=='\\');
 593         lastWasSO    = (*s==SO);
 594         for (; *ch; c = *ch++)
 595             putChr(*ch);
 596         lastWasDigit = (isascii(c) && isdigit(c));
 597     }
 598     putChr('\"');
 599 }
 600
 601 /* --------------------------------------------------------------------------
 602  * Print type expression:
 603  * ------------------------------------------------------------------------*/
 604
 605 static Void local putSigType(t)         /* print (possibly) generic type   */
 606 Cell t; {
 607     Int fr = 0;
 608     if (isPolyType(t)) {
 609         Kinds ks = polySigOf(t);
 610         for (; isAp(ks); ks=tl(ks))
 611             fr++;
 612         t = monotypeOf(t);
 613     }
 614
 615     putType(t,NEVER,fr);                /* Finally, print rest of type ... */
 616 }
 617
 618 static Void local putContext(ps,qs,fr)  /* print context list              */
 619 List ps;
 620 List qs;
 621 Int  fr; {
 622     Int len = length(ps) + length(qs);
 623     Int c   = len;
 624     if (len!=1) {
 625         putChr('(');
 626     }
 627     for (; nonNull(ps); ps=tl(ps)) {
 628         putPred(hd(ps),fr);
 629         if (--c > 0) {
 630             putStr(", ");
 631         }
 632     }
 633     for (; nonNull(qs); qs=tl(qs)) {
 634         putPred(hd(qs),fr);
 635         if (--c > 0) {
 636             putStr(", ");
 637         }
 638     }
 639     if (len!=1) {
 640         putChr(')');
 641     }
 642 }
 643
 644 static Void local putPred(pi,fr)        /* Output predicate                */
 645 Cell pi;
 646 Int  fr; {
 647     if (isAp(pi)) {
 648 #if TREX
 649         if (isExt(fun(pi))) {
 650             putType(arg(pi),ALWAYS,fr);
 651             putChr('\\');
 652             putStr(textToStr(extText(fun(pi))));
 653             return;
 654         }
 655 #endif
 656         putPred(fun(pi),fr);
 657         putChr(' ');
 658         putType(arg(pi),ALWAYS,fr);
 659     }
 660     else if (isClass(pi))
 661         putStr(textToStr(cclass(pi).text));
 662     else if (isCon(pi))
 663         putStr(textToStr(textOf(pi)));
 664     else
 665         putStr("<unknownPredicate>");
 666 }
 667
 668 static Void local putType(t,prec,fr)    /* print nongeneric type expression*/
 669 Cell t;
 670 Int  prec;
 671 Int  fr; {
 672     switch(whatIs(t)) {
 673         case TYCON     : putStr(textToStr(tycon(t).text));
 674                          break;
 675
 676         case TUPLE     : {   Int n = tupleOf(t);
 677                              putChr('(');
 678                              while (--n > 0)
 679                                  putChr(',');
 680                              putChr(')');
 681                          }
 682                          break;
 683
 684         case POLYTYPE  : {   Kinds ks = polySigOf(t);
 685                              OPEN(prec>=ARROW_PREC);
 686                              putStr("forall ");
 687                              for (; isAp(ks); ks=tl(ks)) {
 688                                  putTyVar(fr++);
 689                                  if (isAp(tl(ks)))
 690                                      putChr(',');
 691                              }
 692                              putStr(". ");
 693                              putType(monotypeOf(t),NEVER,fr);
 694                              CLOSE(prec>=ARROW_PREC);
 695                          }
 696                          break;
 697
 698         case CDICTS    :
 699         case QUAL      : OPEN(prec>=ARROW_PREC);
 700                          if (whatIs(snd(snd(t)))==CDICTS) {
 701                              putContext(fst(snd(t)),fst(snd(snd(snd(t)))),fr);
 702                              putStr(" => ");
 703                              putType(snd(snd(snd(snd(t)))),NEVER,fr);
 704                          } else {
 705                              putContext(fst(snd(t)),NIL,fr);
 706                              putStr(" => ");
 707                              putType(snd(snd(t)),NEVER,fr);
 708                          }
 709                          CLOSE(prec>=ARROW_PREC);
 710                          break;
 711
 712         case EXIST     :
 713         case RANK2     : putType(snd(snd(t)),prec,fr);
 714                          break;
 715
 716         case OFFSET    : putTyVar(offsetOf(t));
 717                          break;
 718
 719         case VARIDCELL :
 720         case VAROPCELL : putChr('_');
 721                          unlexVar(textOf(t));
 722                          break;
 723
 724         case INTCELL   : putChr('_');
 725                          putInt(intOf(t));
 726                          break;
 727
 728         case AP       : {   Cell typeHead = getHead(t);
 729                             Bool brackets = (argCount!=0 && prec>=ALWAYS);
 730                             Int  args    = argCount;
 731
 732                             if (typeHead==typeList) {
 733                                 if (argCount==1) {
 734                                     putChr('[');
 735                                     putType(arg(t),NEVER,fr);
 736                                     putChr(']');
 737                                     return;
 738                                 }
 739                             }
 740                             else if (typeHead==typeArrow) {
 741                                 if (argCount==2) {
 742                                     OPEN(prec>=ARROW_PREC);
 743                                     putType(arg(fun(t)),ARROW_PREC,fr);
 744                                     putStr(" -> ");
 745                                     putType(arg(t),NEVER,fr);
 746                                     CLOSE(prec>=ARROW_PREC);
 747                                     return;
 748                                 }
 749                                 else if (argCount==1) {
 750                                     putChr('(');
 751                                     putType(arg(t),ARROW_PREC,fr);
 752                                     putStr("->)");
 753                                     return;
 754                                 }
 755                             }
 756                             else if (isTuple(typeHead)) {
 757                                 if (argCount==tupleOf(typeHead)) {
 758                                     putChr('(');
 759                                     putTupleType(t,fr);
 760                                     putChr(')');
 761                                     return;
 762                                 }
 763                             }
 764 #if TREX
 765                             else if (isExt(typeHead)) {
 766                                 if (args==2) {
 767                                     String punc = "(";
 768                                     do {
 769                                         putStr(punc);
 770                                         punc = ", ";
 771                                         putStr(textToStr(extText(typeHead)));
 772                                         putStr("::");
 773                                         putType(extField(t),NEVER,fr);
 774                                         t        = extRow(t);
 775                                         typeHead = getHead(t);
 776                                     } while (isExt(typeHead) && argCount==2);
 777                                     if (t!=typeNoRow) {
 778                                         putStr(" | ");
 779                                         putType(t,NEVER,fr);
 780                                     }
 781                                     putChr(')');
 782                                     return;
 783                                 }
 784                                 else if (args<2)
 785                                     internal("putExt");
 786                                 else
 787                                     args-=2;
 788                             }
 789 #endif
 790                             OPEN(brackets);
 791                             putApType(t,args,fr);
 792                             CLOSE(brackets);
 793                         }
 794                         break;
 795
 796         default       : putStr("(bad type)");
 797     }
 798 }
 799
 800 static Void local putTyVar(n)           /* print type variable             */
 801 Int n; {
 802     static String alphabet              /* for the benefit of EBCDIC :-)   */
 803                 ="abcdefghijklmnopqrstuvwxyz";
 804     putChr(alphabet[n%26]);
 805     if (n /= 26)                        /* just in case there are > 26 vars*/
 806         putInt(n);
 807 }
 808
 809 static Bool local putTupleType(e,fr)    /* print tuple of types, returning */
 810 Cell e;                                 /* TRUE if something was printed,  */
 811 Int  fr; {                              /* FALSE otherwise; used to control*/
 812     if (isAp(e)) {                      /* printing of intermed. commas    */
 813         if (putTupleType(fun(e),fr))
 814             putChr(',');
 815         putType(arg(e),NEVER,fr);
 816         return TRUE;
 817     }
 818     return FALSE;
 819 }
 820
 821 static Void local putApType(t,n,fr)     /* print type application          */
 822 Cell t;
 823 Int  n;
 824 Int  fr; {
 825     if (n>0) {
 826         putApType(fun(t),n-1,fr);
 827         putChr(' ');
 828         putType(arg(t),ALWAYS,fr);
 829     }
 830     else
 831         putType(t,ALWAYS,fr);
 832 }
 833
 834 /* --------------------------------------------------------------------------
 835  * Print kind expression:
 836  * ------------------------------------------------------------------------*/
 837
 838 static Void local putKind(k)            /* print kind expression           */
 839 Kind k; {
 840     switch (whatIs(k)) {
 841         case AP      : if (isAp(fst(k))) {
 842                            putChr('(');
 843                            putKind(fst(k));
 844                            putChr(')');
 845                        }
 846                        else
 847                            putKind(fst(k));
 848                        putStr(" -> ");
 849                        putKind(snd(k));
 850                        break;
 851
 852 #if TREX
 853         case ROW     : putStr("row");
 854                        break;
 855 #endif
 856
 857         case STAR    : putChr('*');
 858                        break;
 859
 860         case OFFSET  : putTyVar(offsetOf(k));
 861                        break;
 862
 863         case INTCELL : putChr('_');
 864                        putInt(intOf(k));
 865                        break;
 866
 867         default      : putStr("(bad kind)");
 868     }
 869 }
 870
 871 static Void local putKinds(ks)          /* Print list of kinds             */
 872 Kinds ks; {
 873     if (isNull(ks))
 874         putStr("()");
 875     else if (nonNull(tl(ks))) {
 876         putChr('(');
 877         putKind(hd(ks));
 878         while (nonNull(ks=tl(ks))) {
 879             putChr(',');
 880             putKind(hd(ks));
 881         }
 882         putChr(')');
 883     }
 884     else
 885         putKind(hd(ks));
 886 }
 887
 888 /* --------------------------------------------------------------------------
 889  * Main drivers:
 890  * ------------------------------------------------------------------------*/
 891
 892 Void printExp(fp,e)                     /* print expr on specified stream  */
 893 FILE *fp;
 894 Cell e; {
 895     outputStream = fp;
 896     putDepth     = 0;
 897     put(NEVER,e);
 898 }
 899
 900 Void printType(fp,t)                    /* print type on specified stream  */
 901 FILE *fp;
 902 Cell t; {
 903     outputStream = fp;
 904     putSigType(t);
 905 }
 906
 907 Void printContext(fp,qs)                /* print context on spec. stream   */
 908 FILE *fp;
 909 List qs; {
 910     outputStream = fp;
 911     putContext(qs,NIL,0);
 912 }
 913
 914 Void printPred(fp,pi)                   /* print predicate pi on stream    */
 915 FILE *fp;
 916 Cell pi; {
 917     outputStream = fp;
 918     putPred(pi,0);
 919 }
 920
 921 Void printKind(fp,k)                    /* print kind k on stream          */
 922 FILE *fp;
 923 Kind k; {
 924     outputStream = fp;
 925     putKind(k);
 926 }
 927
 928 Void printKinds(fp,ks)                  /* print list of kinds on stream   */
 929 FILE  *fp;
 930 Kinds ks; {
 931     outputStream = fp;
 932     putKinds(ks);
 933 }
 934
 935 /*-------------------------------------------------------------------------*/