REQUIRED MODIFICATIONS TO GOFER V2.30B

Keith Wansbrough
March 7, 1997.

There are a number of changes that must be made to allow the
implementation of I/O monad transformers.  These changes are
given here to Gofer v2.30b.

**
**** First, changes to Gofer itself:
**

diff --unified=3 OrigGofer/src/gofer.c MyGofer/src/gofer.c
--- OrigGofer/src/gofer.c	Fri Mar 31 22:14:56 1995
+++ MyGofer/src/gofer.c	Fri Oct 25 14:54:45 1996
@@ -77,7 +77,11 @@
     /* charge.  I ask however that you show your appreciation for the many */
     /* hours of work involved by retaining my name in the banner.  Thanks! */
 
-    printf("Gofer Version 2.30b  Copyright (c) Mark P Jones 1991-1995\n\n");
+    printf("Gofer Version 2.30b+  Copyright (c) Mark P Jones 1991-1995\n\n");
+
+    /* '+' added KSW 1996-10-25 to denote addition of primSTSemisafeRun    */
+    /* etc.								   */
+
     fflush(stdout);
     interpreter(argc,argv);
     printf("[Leaving Gofer]\n");
diff --unified=3 OrigGofer/src/prims.c MyGofer/src/prims.c
--- OrigGofer/src/prims.c	Fri Jun 24 04:00:00 1994
+++ MyGofer/src/prims.c	Fri Oct 25 14:58:59 1996
@@ -8,6 +8,11 @@
  * the primitives table and consChar() parts are retained.
  * ------------------------------------------------------------------------*/
 
+/*
+ * primSTSemisafeRun, primSTGetWorld and primSTSetWorld
+ * added by Keith Wansbrough (KSW) 1996-10-22..1996-10-25.
+ */
+
 #if PRIMITIVES_CODE
 #include <ctype.h>
 #if (TURBOC | BCC)
@@ -150,6 +155,9 @@
 
 #if IO_MONAD
 PROTO_PRIM(primSTRun);
+PROTO_PRIM(primSTSemisafeRun);  /* KSW */
+PROTO_PRIM(primSTGetWorld);     /* KSW */
+PROTO_PRIM(primSTSetWorld);     /* KSW */
 PROTO_PRIM(primFst);
 PROTO_PRIM(primSnd);
 PROTO_PRIM(primSTReturn);
@@ -305,6 +313,9 @@
 
 #if IO_MONAD
   {"primSTRun",		1, GofcPrim(primSTRun)},
+  {"primSTSemisafeRun",	2, GofcPrim(primSTSemisafeRun)},  /* KSW */
+  {"primSTGetWorld",	1, GofcPrim(primSTGetWorld)},	  /* KSW */
+  {"primSTSetWorld",	2, GofcPrim(primSTSetWorld)},	  /* KSW */
   {"primFst",		1, NoGofcPrim(primFst)},
   {"primSnd",		1, NoGofcPrim(primSnd)},
   {"primSTReturn",	1, GofcPrim(primSTReturn)},
@@ -1829,6 +1840,23 @@
 	      ap(primArg(1),UNIT));
 }
 
+primFun(primSTSemisafeRun) { /* KSW */	/* ST monad run, explicit world    */
+    Cell m = primArg(2);		/*  :: ST s a -> s -> (a,s)	   */
+    Cell s = primArg(1);
+    updapRoot(m,s);
+}
+
+primFun(primSTGetWorld) {    /* KSW */	/* ST monad get world		   */
+    Cell s = primArg(1);		/*  :: ST s s			   */
+    updapRoot(ap(mkTuple(2),s),s);	/*   = \s -> (s,s)		   */
+}
+ 
+primFun(primSTSetWorld) {    /* KSW */	/* ST monad set world		   */
+    Cell news = primArg(2);		/*  :: s -> ST s ()		   */
+    Cell olds = primArg(1);		/*   = \s -> \_ -> ((),s)	   */
+    updapRoot(ap(mkTuple(2),UNIT),news);
+}
+ 
 primFun(primFst) {			/* fst primitive		   */
     eval(primArg(1));			/*  :: (a,s) -> a		   */
     updateRoot(top());


**
**** Next, changes to the prelude.  These changes assume ccio.prelude is
**** the concatenation of cc.prelude and iomonad.gs in the standard
**** distribution.
**

--- OrigGofer/ccio.prelude	Mon Feb 17 19:06:24 1997
+++ AS-MMS/cc-mod.prelude	Mon Feb 17 19:08:48 1997
@@ -10,6 +10,9 @@
 --
 --    Enhanced prelude for use of overloading with constructor classes.
 --    Based on the Haskell standard prelude version 1.2.
+--
+--    Modified to support semisafeRunST
+--      by Keith Wansbrough KSW 1996-10-22..1996-10-23.
 
 help = "press :? for a list of commands"
 
@@ -950,6 +954,9 @@
 primitive putchar      "primIOPutchar"  :: Char -> IO ()
 primitive thenIO       "primIOBind"     :: IO a -> (a -> IO b) -> IO b
 primitive interleaveST "primSTInter"    :: ST s a -> ST s a
+primitive semisafeRunST "primSTSemisafeRun" :: ST s a -> s -> (a,s)
+primitive getworldST    "primSTGetWorld"    :: ST s s
+primitive setworldST    "primSTSetWorld"    :: s -> ST s ()
 
 instance Eq (MutVar s a) where (==) = mutvarEq
 
**
**** It was also found necessary to increase the index space in Gofer,
**** following the README file in the code used by Liang, Hudak and
**** Jones.  The following is a quote from that file.
**

To run the modular interpreter, you need Gofer version 2.30 compiled
as LARGE_GOFER with the following patch to the prelude.h file:

311c311
< #define NUM_INDEXES        Pick(700,   2000,       2000)
---
> #define NUM_INDEXES        Pick(700,   2000,       10000)

**
**** REFERENCES:
**

@MastersThesis{
   Wansbrough97:Modular,
   author="Keith Wansbrough",
   title="A Modular Monadic Action Semantics",
   school="Department of Computer Science, University of Auckland",
   year="1997",
   month=feb,
   documentURL="http://www.cs.auckland.ac.nz/~kwan001/thesis/index.html",
}

@InProceedings{
   Liang*95:Monad,
   author="Sheng Liang and Paul Hudak and Mark Jones",
   title="Monad Transformers and Modular Interpreters",
   booktitle="Conference Record of {POPL} '95: 22nd {ACM}
      {SIGPLAN}-{SIGACT} Symposium on {P}rinciples of {P}rogramming
      {L}anguages, San Francisco, California, January {22--25}, 1995",
   year="1995",
   pages="{333--343}",
   publisher="{ACM} Press",
   address="New York",
}


--Keith Wansbrough.