ghc/interpreter/output.c

   1
   2 /* --------------------------------------------------------------------------
   3  * Unparse expressions and types - for use in error messages, type checker
   4  * and for debugging.
   5  *
   6  * The Hugs 98 system is Copyright (c) Mark P Jones, Alastair Reid, the
   7  * Yale Haskell Group, and the Oregon Graduate Institute of Science and
   8  * Technology, 1994-1999, All rights reserved.  It is distributed as
   9  * free software under the license in the file "License", which is
  10  * included in the distribution.
  11  *
  12  * $RCSfile: output.c,v $
  13  * $Revision: 1.17 $
  14  * $Date: 2000/03/23 14:54:21 $
  15  * ------------------------------------------------------------------------*/
  16
  17 #include "hugsbasictypes.h"
  18 #include "storage.h"
  19 #include "connect.h"
  20 #include "errors.h"
  21 #include <ctype.h>
  22
  23 #define DEPTH_LIMIT     15
  24
  25 /* --------------------------------------------------------------------------
  26  * Local function prototypes:
  27  * ------------------------------------------------------------------------*/
  28
  29 static Void local put            ( Int,Cell );
  30 static Void local putFlds        ( Cell,List );
  31 static Void local putComp        ( Cell,List );
  32 static Void local putQual        ( Cell );
  33 static Bool local isDictVal      ( Cell );
  34 static Cell local maySkipDict    ( Cell );
  35 static Void local putAp          ( Int,Cell );
  36 static Void local putOverInfix   ( Int,Text,Syntax,Cell );
  37 static Void local putInfix       ( Int,Text,Syntax,Cell,Cell );
  38 static Void local putSimpleAp    ( Cell,Int );
  39 static Void local putTuple       ( Int,Cell );
  40 static Int  local unusedTups     ( Int,Cell );
  41 static Void local unlexOp        ( Text );
  42
  43 static Void local putSigType     ( Cell );
  44 static Void local putContext     ( List,List,Int );
  45 static Void local putPred        ( Cell,Int );
  46 static Void local putType        ( Cell,Int,Int );
  47 static Void local putTyVar       ( Int );
  48 static Bool local putTupleType   ( Cell,Int );
  49 static Void local putApType      ( Type,Int,Int );
  50
  51 static Void local putKind        ( Kind );
  52 static Void local putKinds       ( Kinds );
  53
  54
  55 /* --------------------------------------------------------------------------
  56  * Basic output routines:
  57  * ------------------------------------------------------------------------*/
  58
  59 FILE *outputStream;                    /* current output stream            */
  60 Int  outColumn = 0;                    /* current output column number     */
  61
  62 #define OPEN(b)    if (b) putChr('(');
  63 #define CLOSE(b)   if (b) putChr(')');
  64
  65 Void putChr(c)                         /* print single character           */
  66 Int c; {
  67     Putc(c,outputStream);
  68     outColumn++;
  69 }
  70
  71 Void putStr(s)                        /* print string                     */
  72 String s; {
  73     for (; *s; s++) {
  74         Putc(*s,outputStream);
  75         outColumn++;
  76     }
  77 }
  78
  79 Void putInt(n)                        /* print integer                    */
  80 Int n; {
  81     static char intBuf[16];
  82     sprintf(intBuf,"%d",n);
  83     putStr(intBuf);
  84 }
  85
  86 Void putPtr(p)                        /* print pointer                    */
  87 Ptr p; {
  88     static char intBuf[16];
  89     sprintf(intBuf,"%p",p);
  90     putStr(intBuf);
  91 }
  92
  93 /* --------------------------------------------------------------------------
  94  * Precedence values (See Haskell 1.3 report, p.12):
  95  * ------------------------------------------------------------------------*/
  96
  97 #define ALWAYS      FUN_PREC           /* Always use parens (unless atomic)*/
  98                                        /* User defined operators have prec */
  99                                        /* in the range MIN_PREC..MAX_PREC  */
 100 #define ARROW_PREC  MAX_PREC           /* for printing -> in type exprs    */
 101 #define COCO_PREC   (MIN_PREC-1)       /* :: is left assoc, low precedence */
 102 #define COND_PREC   (MIN_PREC-2)       /* conditional expressions          */
 103 #define WHERE_PREC  (MIN_PREC-3)       /* where expressions                */
 104 #define LAM_PREC    (MIN_PREC-4)       /* lambda abstraction               */
 105 #define NEVER       LAM_PREC           /* Never use parentheses            */
 106
 107
 108 /* --------------------------------------------------------------------------
 109  * Print an expression (used to display context of type errors):
 110  * ------------------------------------------------------------------------*/
 111
 112 static Int putDepth = 0;               /* limits depth of printing DBG     */
 113
 114 static Void local put(d,e)             /* print expression e in context of */
 115 Int  d;                                /* operator of precedence d         */
 116 Cell e; {
 117     List xs;
 118
 119     if (putDepth>DEPTH_LIMIT) {
 120         putStr("...");
 121         return;
 122     }
 123     else
 124         putDepth++;
 125
 126     switch (whatIs(e)) {
 127         case FINLIST    : putChr('[');
 128                           xs = snd(e);
 129                           if (nonNull(xs)) {
 130                               put(NEVER,hd(xs));
 131                               while (nonNull(xs=tl(xs))) {
 132                                   putChr(',');
 133                                   put(NEVER,hd(xs));
 134                               }
 135                           }
 136                           putChr(']');
 137                           break;
 138
 139         case AP         : putAp(d,e);
 140                           break;
 141
 142         case NAME       : unlexVar(name(e).text);
 143                           break;
 144
 145         case VARIDCELL  :
 146         case VAROPCELL  :
 147         case DICTVAR    :
 148         case CONIDCELL  :
 149         case CONOPCELL  : unlexVar(textOf(e));
 150                           break;
 151
 152 #if IPARAM
 153         case IPVAR      : putChr('?');
 154                           unlexVar(textOf(e));
 155                           break;
 156
 157         case WITHEXP    : OPEN(d>WHERE_PREC);
 158                           putStr("dlet {...} in ");
 159                           put(WHERE_PREC+1,fst(snd(e)));
 160                           CLOSE(d>WHERE_PREC);
 161                           break;
 162 #endif
 163
 164 #if TREX
 165         case RECSEL     : putChr('#');
 166                           unlexVar(extText(snd(e)));
 167                           break;
 168 #endif
 169
 170         case FREECELL   : putStr("{free!}");
 171                           break;
 172
 173         case TUPLE      : putTuple(tupleOf(e),e);
 174                           break;
 175
 176         case WILDCARD   : putChr('_');
 177                           break;
 178
 179         case ASPAT      : put(NEVER,fst(snd(e)));
 180                           putChr('@');
 181                           put(ALWAYS,snd(snd(e)));
 182                           break;
 183
 184         case LAZYPAT    : putChr('~');
 185                           put(ALWAYS,snd(e));
 186                           break;
 187
 188         case DOCOMP     : putStr("do {...}");
 189                           break;
 190
 191         case COMP       : putComp(fst(snd(e)),snd(snd(e)));
 192                           break;
 193
 194         case MONADCOMP  : putComp(fst(snd(snd(e))),snd(snd(snd(e))));
 195                           break;
 196
 197         case CHARCELL   : unlexCharConst(charOf(e));
 198                           break;
 199
 200         case INTCELL    : {   Int i = intOf(e);
 201                               if (i<0 && d>=UMINUS_PREC) putChr('(');
 202                               putInt(i);
 203                               if (i<0 && d>=UMINUS_PREC) putChr(')');
 204                           }
 205                           break;
 206
 207         case FLOATCELL  : {   Float f = floatOf(e);
 208                               if (f<0 && d>=UMINUS_PREC) putChr('(');
 209                               putStr(floatToString(e));
 210                               if (f<0 && d>=UMINUS_PREC) putChr(')');
 211                           }
 212                           break;
 213
 214         case STRCELL    : unlexStrConst(textOf(e));
 215                           break;
 216
 217         case LETREC     : OPEN(d>WHERE_PREC);
 218 #if 0
 219                           putStr("let {");
 220                           put(NEVER,fst(snd(e)));
 221                           putStr("} in ");
 222 #else
 223                           putStr("let {...} in ");
 224 #endif
 225                           put(WHERE_PREC+1,snd(snd(e)));
 226                           CLOSE(d>WHERE_PREC);
 227                           break;
 228
 229         case COND       : OPEN(d>COND_PREC);
 230                           putStr("if ");
 231                           put(COND_PREC+1,fst3(snd(e)));
 232                           putStr(" then ");
 233                           put(COND_PREC+1,snd3(snd(e)));
 234                           putStr(" else ");
 235                           put(COND_PREC+1,thd3(snd(e)));
 236                           CLOSE(d>COND_PREC);
 237                           break;
 238
 239         case LAMBDA     : xs = fst(snd(e));
 240                           if (whatIs(xs)==BIGLAM)
 241                               xs = snd(snd(xs));
 242                           while (nonNull(xs) && isDictVal(hd(xs)))
 243                               xs = tl(xs);
 244                           if (isNull(xs)) {
 245                               put(d,snd(snd(snd(e))));
 246                               break;
 247                           }
 248                           OPEN(d>LAM_PREC);
 249                           putChr('\\');
 250                           if (nonNull(xs)) {
 251                               put(ALWAYS,hd(xs));
 252                               while (nonNull(xs=tl(xs))) {
 253                                   putChr(' ');
 254                                   put(ALWAYS,hd(xs));
 255                               }
 256                           }
 257                           putStr(" -> ");
 258                           put(LAM_PREC,snd(snd(snd(e))));
 259                           CLOSE(d>LAM_PREC);
 260                           break;
 261
 262         case ESIGN      : OPEN(d>COCO_PREC);
 263                           put(COCO_PREC,fst(snd(e)));
 264                           putStr(" :: ");
 265                           putSigType(snd(snd(e)));
 266                           CLOSE(d>COCO_PREC);
 267                           break;
 268
 269         case BIGLAM     : put(d,snd(snd(e)));
 270                           break;
 271
 272         case CASE       : putStr("case ");
 273                           put(NEVER,fst(snd(e)));
 274 #if 0
 275                           putStr(" of {");
 276                           put(NEVER,snd(snd(e)));
 277                           putChr('}');
 278 #else
 279                           putStr(" of {...}");
 280 #endif
 281                           break;
 282
 283         case CONFLDS    : putFlds(fst(snd(e)),snd(snd(e)));
 284                           break;
 285
 286         case UPDFLDS    : putFlds(fst3(snd(e)),thd3(snd(e)));
 287                           break;
 288
 289         default         : /*internal("put");*/
 290                           putChr('$');
 291                           putInt(e);
 292                           break;
 293     }
 294     putDepth--;
 295 }
 296
 297 static Void local putFlds(exp,fs)       /* Output exp using labelled fields*/
 298 Cell exp;
 299 List fs; {
 300     put(ALWAYS,exp);
 301     putChr('{');
 302     for (; nonNull(fs); fs=tl(fs)) {
 303         Cell v = hd(fs);
 304         if (isVar(v))
 305             put(NEVER,v);
 306         else {
 307             Cell f = fst(v);
 308             Cell e = snd(v);
 309             Text t = isName(f) ? name(f).text :
 310                      isVar(f)  ? textOf(f)    : inventText();
 311             Text s = isName(e) ? name(e).text :
 312                      isVar(e)  ? textOf(e)    : inventText();
 313
 314             put(NEVER,f);
 315             if (haskell98 || s!=t) {
 316                 putStr(" = ");
 317                 put(NEVER,e);
 318             }
 319         }
 320         if (nonNull(tl(fs)))
 321             putStr(", ");
 322     }
 323     putChr('}');
 324 }
 325
 326 static Void local putComp(e,qs)         /* print comprehension             */
 327 Cell e;
 328 List qs; {
 329     putStr("[ ");
 330     put(NEVER,e);
 331     if (nonNull(qs)) {
 332         putStr(" | ");
 333         putQual(hd(qs));
 334         while (nonNull(qs=tl(qs))) {
 335             putStr(", ");
 336             putQual(hd(qs));
 337         }
 338     }
 339     putStr(" ]");
 340 }
 341
 342 static Void local putQual(q)            /* print list comp qualifier       */
 343 Cell q; {
 344     switch (whatIs(q)) {
 345         case BOOLQUAL : put(NEVER,snd(q));
 346                         return;
 347
 348         case QWHERE   : putStr("let {...}");
 349                         return;
 350
 351         case FROMQUAL : put(ALWAYS,fst(snd(q)));
 352                         putStr("<-");
 353                         put(NEVER,snd(snd(q)));
 354                         return;
 355     }
 356 }
 357
 358 static Bool local isDictVal(e)          /* Look for dictionary value       */
 359 Cell e; {
 360 #if 0   /* was !DEBUG_CODE -- is it necessary? */
 361     Cell h = getHead(e);
 362     switch (whatIs(h)) {
 363         case DICTVAR : return TRUE;
 364         case NAME    : return isDfun(h);
 365     }
 366 #endif
 367     return FALSE;
 368 }
 369
 370 static Cell local maySkipDict(e)        /* descend function application,   */
 371 Cell e; {                               /* ignoring dict aps               */
 372     while (isAp(e) && isDictVal(arg(e)))
 373         e = fun(e);
 374     return e;
 375 }
 376
 377 static Void local putAp(d,e)            /* print application (args>=1)     */
 378 Int  d;
 379 Cell e; {
 380     Cell   h;
 381     Text   t = 0;                       /* bogus init to keep gcc -O happy */
 382     Syntax sy;
 383     Int    args = 0;
 384
 385     for (h=e; isAp(h); h=fun(h))        /* find head of expression, looking*/
 386         if (!isDictVal(arg(h)))         /* for dictionary arguments        */
 387             args++;
 388
 389     if (args==0) {                      /* Special case when *all* args    */
 390         put(d,h);                       /* are dictionary values           */
 391         return;
 392     }
 393
 394     switch (whatIs(h)) {
 395         case ADDPAT     : if (args==1)
 396                               putInfix(d,textPlus,syntaxOf(namePlus),
 397                                          arg(e),mkInt(intValOf(fun(e))));
 398                           else
 399                               putStr("ADDPAT");
 400                           return;
 401
 402         case TUPLE      : OPEN(args>tupleOf(h) && d>=FUN_PREC);
 403                           putTuple(tupleOf(h),e);
 404                           CLOSE(args>tupleOf(h) && d>=FUN_PREC);
 405                           return;
 406
 407         case NAME       : if (args==1 &&
 408                               ((h==nameFromInt     && isInt(arg(e)))    ||
 409                                (h==nameFromDouble  && isFloat(arg(e))))) {
 410                               put(d,arg(e));
 411                               return;
 412                           }
 413                           t  = name(h).text;
 414                           sy = syntaxOf(h);
 415                           break;
 416
 417         case VARIDCELL  :
 418         case VAROPCELL  :
 419         case DICTVAR    :
 420         case CONIDCELL  :
 421         case CONOPCELL  : sy = defaultSyntax(t = textOf(h));
 422                           break;
 423
 424 #if TREX
 425         case EXT        : if (args==2) {
 426                               String punc = "(";
 427                               do {
 428                                   putStr(punc);
 429                                   punc = ", ";
 430                                   putStr(textToStr(extText(h)));
 431                                   putStr("=");
 432                                   put(NEVER,extField(e));
 433                                   args = 0;
 434                                   e    = extRow(e);
 435                                   for (h=e; isAp(h); h=fun(h))
 436                                       if (!isDictVal(arg(h)))
 437                                           args++;
 438                               } while (isExt(h) && args==2);
 439                               if (e!=nameNoRec) {
 440                                   putStr(" | ");
 441                                   put(NEVER,e);
 442                               }
 443                               putChr(')');
 444                               return;
 445                           }
 446                           else if (args<2)
 447                               internal("putExt");
 448                           else
 449                               args-=2;
 450                           break;
 451 #endif
 452
 453         default         : sy = APPLIC;
 454                           break;
 455     }
 456
 457     e = maySkipDict(e);
 458
 459     if (sy==APPLIC) {                   /* print simple application        */
 460         OPEN(d>=FUN_PREC);
 461         putSimpleAp(e,args);
 462         CLOSE(d>=FUN_PREC);
 463         return;
 464     }
 465     else if (args==1) {                 /* print section of the form (e+)  */
 466         putChr('(');
 467         put(FUN_PREC-1,arg(e));
 468         putChr(' ');
 469         unlexOp(t);
 470         putChr(')');
 471     }
 472     else if (args==2)                  /* infix expr of the form e1 + e2   */
 473         putInfix(d,t,sy,arg(maySkipDict(fun(e))),arg(e));
 474     else {                             /* o/w (e1 + e2) e3 ... en   (n>=3) */
 475         OPEN(d>=FUN_PREC);
 476         putOverInfix(args,t,sy,e);
 477         CLOSE(d>=FUN_PREC);
 478     }
 479 }
 480
 481 static Void local putOverInfix(args,t,sy,e)
 482 Int    args;                           /* infix applied to >= 3 arguments  */
 483 Text   t;
 484 Syntax sy;
 485 Cell   e; {
 486     if (args>2) {
 487         putOverInfix(args-1,t,sy,maySkipDict(fun(e)));
 488         putChr(' ');
 489         put(FUN_PREC,arg(e));
 490     }
 491     else
 492         putInfix(ALWAYS,t,sy,arg(maySkipDict(fun(e))),arg(e));
 493 }
 494
 495 static Void local putInfix(d,t,sy,e,f)  /* print infix expression          */
 496 Int    d;
 497 Text   t;                               /* Infix operator symbol           */
 498 Syntax sy;                              /* with name t, syntax s           */
 499 Cell   e, f; {                          /* Left and right operands         */
 500     Syntax a = assocOf(sy);
 501     Int    p = precOf(sy);
 502
 503     OPEN(d>p);
 504     put((a==LEFT_ASS ? p : 1+p), e);
 505     putChr(' ');
 506     unlexOp(t);
 507     putChr(' ');
 508     put((a==RIGHT_ASS ? p : 1+p), f);
 509     CLOSE(d>p);
 510 }
 511
 512 static Void local putSimpleAp(e,n)      /* print application e0 e1 ... en  */
 513 Cell e;
 514 Int  n; {
 515     if (n>0) {
 516         putSimpleAp(maySkipDict(fun(e)),n-1);
 517         putChr(' ');
 518         put(FUN_PREC,arg(e));
 519     }
 520     else
 521         put(FUN_PREC,e);
 522 }
 523
 524 static Void local putTuple(ts,e)        /* Print tuple expression, allowing*/
 525 Int  ts;                                /* for possibility of either too   */
 526 Cell e; {                               /* few or too many args to constr  */
 527     Int i;
 528     putChr('(');
 529     if ((i=unusedTups(ts,e))>0) {
 530         while (--i>0)
 531             putChr(',');
 532         putChr(')');
 533     }
 534 }
 535
 536 static Int local unusedTups(ts,e)       /* print first part of tuple expr  */
 537 Int  ts;                                /* returning number of constructor */
 538 Cell e; {                               /* args not yet printed ...        */
 539     if (isAp(e)) {
 540         if ((ts=unusedTups(ts,fun(e))-1)>=0) {
 541             put(NEVER,arg(e));
 542             putChr(ts>0?',':')');
 543         }
 544         else {
 545             putChr(' ');
 546             put(FUN_PREC,arg(e));
 547         }
 548     }
 549     return ts;
 550 }
 551
 552 Void unlexVarStr(s)
 553 String s; {
 554     if ((isascii((int)(s[0])) && isalpha((int)(s[0])))
 555         || s[0]=='_' || s[0]=='[' || s[0]=='('
 556         || s[0]=='$'
 557         || (s[0]==':' && s[1]=='D')
 558        )
 559         putStr(s);
 560     else {
 561         putChr('(');
 562         putStr(s);
 563         putChr(')');
 564     }
 565 }
 566
 567 Void unlexVar(t)                       /* print text as a variable name    */
 568 Text t; {                              /* operator symbols must be enclosed*/
 569     unlexVarStr(textToStr(t));         /* in parentheses... except [] ...  */
 570 }
 571
 572 static Void local unlexOp(t)           /* print text as operator name      */
 573 Text t; {                              /* alpha numeric symbols must be    */
 574     String s = textToStr(t);           /* enclosed by backquotes           */
 575
 576     if (isascii((int)(s[0])) && isalpha((int)(s[0]))) {
 577         putChr('`');
 578         putStr(s);
 579         putChr('`');
 580     }
 581     else
 582         putStr(s);
 583 }
 584
 585 Void unlexCharConst(c)
 586 Cell c; {
 587     putChr('\'');
 588     putStr(unlexChar(c,'\''));
 589     putChr('\'');
 590 }
 591
 592 Void unlexStrConst(t)
 593 Text t; {
 594     String s            = textToStr(t);
 595     static Char SO      = 14;          /* ASCII code for '\SO'             */
 596     Bool   lastWasSO    = FALSE;
 597     Bool   lastWasDigit = FALSE;
 598     Bool   lastWasEsc   = FALSE;
 599
 600     putChr('\"');
 601     for (; *s; s++) {
 602         String ch = unlexChar(*s,'\"');
 603         Char   c  = ' ';
 604
 605         if ((lastWasSO && *ch=='H') ||
 606                 (lastWasEsc && lastWasDigit
 607                  && isascii((int)(*ch)) && isdigit((int)(*ch))))
 608             putStr("\\&");
 609
 610         lastWasEsc   = (*ch=='\\');
 611         lastWasSO    = (*s==SO);
 612         for (; *ch; c = *ch++)
 613             putChr(*ch);
 614         lastWasDigit = (isascii(c) && isdigit(c));
 615     }
 616     putChr('\"');
 617 }
 618
 619 /* --------------------------------------------------------------------------
 620  * Print type expression:
 621  * ------------------------------------------------------------------------*/
 622
 623 static Void local putSigType(t)         /* print (possibly) generic type   */
 624 Cell t; {
 625     Int fr = 0;
 626     if (isPolyType(t)) {
 627         Kinds ks = polySigOf(t);
 628         for (; isAp(ks); ks=tl(ks))
 629             fr++;
 630         t = monotypeOf(t);
 631     }
 632
 633     putType(t,NEVER,fr);                /* Finally, print rest of type ... */
 634 }
 635
 636 static Void local putContext(ps,qs,fr)  /* print context list              */
 637 List ps;
 638 List qs;
 639 Int  fr; {
 640     Int len = length(ps) + length(qs);
 641     Int c   = len;
 642 #if IPARAM
 643     Bool useParens = len!=1 || isIP(fun(hd(ps)));
 644 #else
 645     Bool useParens = len!=1;
 646 #endif
 647     if (useParens)
 648         putChr('(');
 649     for (; nonNull(ps); ps=tl(ps)) {
 650         putPred(hd(ps),fr);
 651         if (--c > 0) {
 652             putStr(", ");
 653         }
 654     }
 655     for (; nonNull(qs); qs=tl(qs)) {
 656         putPred(hd(qs),fr);
 657         if (--c > 0) {
 658             putStr(", ");
 659         }
 660     }
 661     if (useParens)
 662         putChr(')');
 663 }
 664
 665 static Void local putPred(pi,fr)        /* Output predicate                */
 666 Cell pi;
 667 Int  fr; {
 668     if (isAp(pi)) {
 669 #if TREX
 670         if (isExt(fun(pi))) {
 671             putType(arg(pi),ALWAYS,fr);
 672             putChr('\\');
 673             putStr(textToStr(extText(fun(pi))));
 674             return;
 675         }
 676 #endif
 677 #if IPARAM
 678         if (whatIs(fun(pi)) == IPCELL) {
 679             putChr('?');
 680             putPred(fun(pi),fr);
 681             putStr(" :: ");
 682             putType(arg(pi),NEVER,fr);
 683             return;
 684         }
 685 #endif
 686         putPred(fun(pi),fr);
 687         putChr(' ');
 688         putType(arg(pi),ALWAYS,fr);
 689     }
 690     else if (isClass(pi))
 691         putStr(textToStr(cclass(pi).text));
 692     else if (isCon(pi))
 693         putStr(textToStr(textOf(pi)));
 694 #if IPARAM
 695     else if (whatIs(pi) == IPCELL)
 696         unlexVar(textOf(pi));
 697 #endif
 698     else
 699         putStr("<unknownPredicate>");
 700 }
 701
 702 static Void local putType(t,prec,fr)    /* print nongeneric type expression*/
 703 Cell t;
 704 Int  prec;
 705 Int  fr; {
 706     switch(whatIs(t)) {
 707         case TYCON     : putStr(textToStr(tycon(t).text));
 708                          break;
 709
 710         case TUPLE     : {   Int n = tupleOf(t);
 711                              putChr('(');
 712                              while (--n > 0)
 713                                  putChr(',');
 714                              putChr(')');
 715                          }
 716                          break;
 717
 718         case POLYTYPE  : {   Kinds ks = polySigOf(t);
 719                              OPEN(prec>=ARROW_PREC);
 720                              putStr("forall ");
 721                              for (; isAp(ks); ks=tl(ks)) {
 722                                  putTyVar(fr++);
 723                                  if (isAp(tl(ks)))
 724                                      putChr(' ');
 725                              }
 726                              putStr(". ");
 727                              putType(monotypeOf(t),NEVER,fr);
 728                              CLOSE(prec>=ARROW_PREC);
 729                          }
 730                          break;
 731
 732         case CDICTS    :
 733         case QUAL      : OPEN(prec>=ARROW_PREC);
 734                          if (whatIs(snd(snd(t)))==CDICTS) {
 735                              putContext(fst(snd(t)),fst(snd(snd(snd(t)))),fr);
 736                              putStr(" => ");
 737                              putType(snd(snd(snd(snd(t)))),NEVER,fr);
 738                          } else {
 739                              putContext(fst(snd(t)),NIL,fr);
 740                              putStr(" => ");
 741                              putType(snd(snd(t)),NEVER,fr);
 742                          }
 743                          CLOSE(prec>=ARROW_PREC);
 744                          break;
 745
 746         case EXIST     :
 747         case RANK2     : putType(snd(snd(t)),prec,fr);
 748                          break;
 749
 750         case OFFSET    : putTyVar(offsetOf(t));
 751                          break;
 752
 753         case VARIDCELL :
 754         case VAROPCELL : putChr('_');
 755                          unlexVar(textOf(t));
 756                          break;
 757
 758         case INTCELL   : putChr('_');
 759                          putInt(intOf(t));
 760                          break;
 761
 762         case AP       : {   Cell typeHead = getHead(t);
 763                             Bool brackets = (argCount!=0 && prec>=ALWAYS);
 764                             Int  args    = argCount;
 765
 766                             if (typeHead==typeList) {
 767                                 if (argCount==1) {
 768                                     putChr('[');
 769                                     putType(arg(t),NEVER,fr);
 770                                     putChr(']');
 771                                     return;
 772                                 }
 773                             }
 774                             else if (typeHead==typeArrow) {
 775                                 if (argCount==2) {
 776                                     OPEN(prec>=ARROW_PREC);
 777                                     putType(arg(fun(t)),ARROW_PREC,fr);
 778                                     putStr(" -> ");
 779                                     putType(arg(t),NEVER,fr);
 780                                     CLOSE(prec>=ARROW_PREC);
 781                                     return;
 782                                 }
 783 #if 0
 784                                 else if (argCount==1) {
 785                                     putChr('(');
 786                                     putType(arg(t),ARROW_PREC,fr);
 787                                     putStr("->)");
 788                                     return;
 789                                 }
 790 #endif
 791                             }
 792                             else if (isTuple(typeHead)) {
 793                                 if (argCount==tupleOf(typeHead)) {
 794                                     putChr('(');
 795                                     putTupleType(t,fr);
 796                                     putChr(')');
 797                                     return;
 798                                 }
 799                             }
 800 #if TREX
 801                             else if (isExt(typeHead)) {
 802                                 if (args==2) {
 803                                     String punc = "(";
 804                                     do {
 805                                         putStr(punc);
 806                                         punc = ", ";
 807                                         putStr(textToStr(extText(typeHead)));
 808                                         putStr(" :: ");
 809                                         putType(extField(t),NEVER,fr);
 810                                         t        = extRow(t);
 811                                         typeHead = getHead(t);
 812                                     } while (isExt(typeHead) && argCount==2);
 813                                     if (t!=typeNoRow) {
 814                                         putStr(" | ");
 815                                         putType(t,NEVER,fr);
 816                                     }
 817                                     putChr(')');
 818                                     return;
 819                                 }
 820                                 else if (args<2)
 821                                     internal("putExt");
 822                                 else
 823                                     args-=2;
 824                             }
 825 #endif
 826                             OPEN(brackets);
 827                             putApType(t,args,fr);
 828                             CLOSE(brackets);
 829                         }
 830                         break;
 831
 832         default       : putStr("(bad type)");
 833     }
 834 }
 835
 836 static Void local putTyVar(n)           /* print type variable             */
 837 Int n; {
 838     static String alphabet              /* for the benefit of EBCDIC :-)   */
 839                 ="abcdefghijklmnopqrstuvwxyz";
 840     putChr(alphabet[n%26]);
 841     if (n /= 26)                        /* just in case there are > 26 vars*/
 842         putInt(n);
 843 }
 844
 845 static Bool local putTupleType(e,fr)    /* print tuple of types, returning */
 846 Cell e;                                 /* TRUE if something was printed,  */
 847 Int  fr; {                              /* FALSE otherwise; used to control*/
 848     if (isAp(e)) {                      /* printing of intermed. commas    */
 849         if (putTupleType(fun(e),fr))
 850             putChr(',');
 851         putType(arg(e),NEVER,fr);
 852         return TRUE;
 853     }
 854     return FALSE;
 855 }
 856
 857 static Void local putApType(t,n,fr)     /* print type application          */
 858 Cell t;
 859 Int  n;
 860 Int  fr; {
 861     if (n>0) {
 862         putApType(fun(t),n-1,fr);
 863         putChr(' ');
 864         putType(arg(t),ALWAYS,fr);
 865     }
 866     else
 867         putType(t,ALWAYS,fr);
 868 }
 869
 870 /* --------------------------------------------------------------------------
 871  * Print kind expression:
 872  * ------------------------------------------------------------------------*/
 873
 874 static Void local putKind(k)            /* print kind expression           */
 875 Kind k; {
 876     switch (whatIs(k)) {
 877         case AP      : if (isAp(fst(k))) {
 878                            putChr('(');
 879                            putKind(fst(k));
 880                            putChr(')');
 881                        }
 882                        else
 883                            putKind(fst(k));
 884                        putStr(" -> ");
 885                        putKind(snd(k));
 886                        break;
 887
 888 #if TREX
 889         case ROW     : putStr("row");
 890                        break;
 891 #endif
 892
 893         case STAR    : putChr('*');
 894                        break;
 895
 896         case OFFSET  : putTyVar(offsetOf(k));
 897                        break;
 898
 899         case INTCELL : putChr('_');
 900                        putInt(intOf(k));
 901                        break;
 902
 903         default      : putStr("(bad kind)");
 904     }
 905 }
 906
 907 static Void local putKinds(ks)          /* Print list of kinds             */
 908 Kinds ks; {
 909     if (isNull(ks))
 910         putStr("()");
 911     else if (nonNull(tl(ks))) {
 912         putChr('(');
 913         putKind(hd(ks));
 914         while (nonNull(ks=tl(ks))) {
 915             putChr(',');
 916             putKind(hd(ks));
 917         }
 918         putChr(')');
 919     }
 920     else
 921         putKind(hd(ks));
 922 }
 923
 924 /* --------------------------------------------------------------------------
 925  * Main drivers:
 926  * ------------------------------------------------------------------------*/
 927
 928 FILE *mystdout ( Void ) {
 929   /* We use this from the gdb command line when debugging */
 930   return stdout;
 931 }
 932
 933 Void printExp(fp,e)                     /* print expr on specified stream  */
 934 FILE *fp;
 935 Cell e; {
 936     outputStream = fp;
 937     putDepth     = 0;
 938     put(NEVER,e);
 939 }
 940
 941 Void printType(fp,t)                    /* print type on specified stream  */
 942 FILE *fp;
 943 Cell t; {
 944     outputStream = fp;
 945     putSigType(t);
 946 }
 947
 948 Void printContext(fp,qs)                /* print context on spec. stream   */
 949 FILE *fp;
 950 List qs; {
 951     outputStream = fp;
 952     putContext(qs,NIL,0);
 953 }
 954
 955 Void printPred(fp,pi)                   /* print predicate pi on stream    */
 956 FILE *fp;
 957 Cell pi; {
 958     outputStream = fp;
 959     putPred(pi,0);
 960 }
 961
 962 Void printKind(fp,k)                    /* print kind k on stream          */
 963 FILE *fp;
 964 Kind k; {
 965     outputStream = fp;
 966     putKind(k);
 967 }
 968
 969 Void printKinds(fp,ks)                  /* print list of kinds on stream   */
 970 FILE  *fp;
 971 Kinds ks; {
 972     outputStream = fp;
 973     putKinds(ks);
 974 }
 975
 976 Void printFD(fp,fd)                     /* print functional dependency     */
 977 FILE* fp;
 978 Pair  fd; {
 979     List us;
 980     outputStream = fp;
 981     for (us=fst(fd); nonNull(us); us=tl(us)) {
 982         putTyVar(offsetOf(hd(us)));
 983         if (nonNull(tl(us))) {
 984             putChr(' ');
 985         }
 986     }
 987     putStr(" -> ");
 988     for (us=snd(fd); nonNull(us); us=tl(us)) {
 989         putTyVar(offsetOf(hd(us)));
 990         if (nonNull(tl(us))) {
 991             putChr(' ');
 992         }
 993     }
 994 }
 995
 996 /*-------------------------------------------------------------------------*/