patch: remove unused futures code

[Ken Raeburn <raeburn@raeburn.org>]

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     Since support for "futures" in C has been completely disabled for  
some
     time, and should be easily implementable in Scheme with the current
     thread support, delete the C code.

     * libguile/futures.c, libguile/futures.h: Delete.
     * libguile/Makefile.am (libguile_la_SOURCES, DOT_X_FILES,
       DOT_DOC_FILES, modinclude_HEADERS): Delete references to  
futures.*
       files.

     * libguile.h: Don't include futures.h.
     * libguile/eval.c: Don't include futures.h.
       (isymnames): Delete "#@future" entry.
       (scm_m_future, s_future, scm_sym_future, unmemoize_future,
       unmemoize_builtin_macro): Delete disabled futures code.
     * libguile/eval.i.c (CEVAL): Delete disabled futures code.
     * libguile/init.c: Don't include futures.h.
       (scm_i_init_guile): Delete disabled futures initialization call.
     * libguile/tags.h (SCM_IM_FUTURE): Delete.
       (SCM_IM_CALL_WITH_VALUES, SCM_IM_ELSE, SCM_IM_ARROW,
       SCM_IM_NIL_COND, SCM_IM_BIND): Renumber.

     * doc/ref/api-scheduling.texi: Delete commented-out node on  
Futures.
     * doc/maint/guile.texi: Delete make-future and future-ref mentions.

The attached patch doesn't include the diffs for the files going away.


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diff --git a/doc/maint/guile.texi b/doc/maint/guile.texi
index 3b5305e..127f0bb 100644
--- a/doc/maint/guile.texi
+++ b/doc/maint/guile.texi
@@ -1750,22 +1750,6 @@ current interfaces.  If a file cannot be opened with the access
 requested, @code{open-file} throws an exception.
 @end deffn
 
-\fmake-future
-@c snarfed from futures.c:89
-@deffn {Scheme Procedure} make-future thunk
-@deffnx {C Function} scm_make_future (thunk)
-Make a future evaluating THUNK.
-@end deffn
-
-\ffuture-ref
-@c snarfed from futures.c:221
-@deffn {Scheme Procedure} future-ref future
-@deffnx {C Function} scm_future_ref (future)
-If the future @var{x} has not been computed yet, compute and
-return @var{x}, otherwise just return the previously computed
-value.
-@end deffn
-
 \fgc-live-object-stats
 @c snarfed from gc.c:276
 @deffn {Scheme Procedure} gc-live-object-stats
diff --git a/doc/ref/api-scheduling.texi b/doc/ref/api-scheduling.texi
index 34697d3..8382ba3 100644
--- a/doc/ref/api-scheduling.texi
+++ b/doc/ref/api-scheduling.texi
@@ -792,39 +792,6 @@ Like @code{scm_with_dynamic_state}, but call @var{func} with
 @var{data}.
 @end deftypefn
 
-@c @node Futures
-@c @subsection Futures
-@c @cindex futures
-
-@c -- Futures are disabled for the time being, see futures.h for an
-@c -- explanation.
-
-@c Futures are a convenient way to run a calculation in a new thread, and
-@c only wait for the result when it's actually needed.
-
-@c Futures are similar to promises (@pxref{Delayed Evaluation}), in that
-@c they allow mainline code to continue immediately.  But @code{delay}
-@c doesn't evaluate at all until forced, whereas @code{future} starts
-@c immediately in a new thread.
-
-@c @deffn {syntax} future expr
-@c Begin evaluating @var{expr} in a new thread, and return a ``future''
-@c object representing the calculation.
-@c @end deffn
-
-@c @deffn {Scheme Procedure} make-future thunk
-@c @deffnx {C Function} scm_make_future (thunk)
-@c Begin evaluating the call @code{(@var{thunk})} in a new thread, and
-@c return a ``future'' object representing the calculation.
-@c @end deffn
-
-@c @deffn {Scheme Procedure} future-ref f
-@c @deffnx {C Function} scm_future_ref (f)
-@c Return the value computed by the future @var{f}.  If @var{f} has not
-@c yet finished executing then wait for it to do so.
-@c @end deffn
-
-
 @node Parallel Forms
 @subsection Parallel forms
 @cindex parallel forms
diff --git a/libguile.h b/libguile.h
index 7967c2b..73b3de7 100644
--- a/libguile.h
+++ b/libguile.h
@@ -51,7 +51,6 @@ extern "C" {
 #include "libguile/filesys.h"
 #include "libguile/fluids.h"
 #include "libguile/fports.h"
-#include "libguile/futures.h"
 #include "libguile/gc.h"
 #include "libguile/gdbint.h"
 #include "libguile/generalized-arrays.h"
diff --git a/libguile/Makefile.am b/libguile/Makefile.am
index 2e8457b..96c66a7 100644
--- a/libguile/Makefile.am
+++ b/libguile/Makefile.am
@@ -131,7 +131,6 @@ libguile_la_SOURCES =				\
 	fluids.c				\
 	fports.c				\
 	frames.c				\
-	futures.c				\
 	gc-malloc.c				\
 	gc.c					\
 	gdbint.c				\
@@ -230,7 +229,6 @@ DOT_X_FILES =					\
 	feature.x				\
 	fluids.x				\
 	fports.x				\
-	futures.x				\
 	gc-malloc.x				\
 	gc.x					\
 	gettext.x				\
@@ -327,7 +325,6 @@ DOT_DOC_FILES = 				\
 	feature.doc				\
 	fluids.doc				\
 	fports.doc				\
-	futures.doc				\
 	gc-malloc.doc				\
 	gc.doc					\
 	gettext.doc				\
@@ -483,7 +480,6 @@ modinclude_HEADERS =				\
 	fluids.h				\
 	fports.h				\
 	frames.h				\
-	futures.h				\
 	gc.h					\
 	gdb_interface.h				\
 	gdbint.h				\
diff --git a/libguile/eval.c b/libguile/eval.c
index 59db429..3c96251 100644
--- a/libguile/eval.c
+++ b/libguile/eval.c
@@ -41,7 +41,6 @@
 #include "libguile/eq.h"
 #include "libguile/feature.h"
 #include "libguile/fluids.h"
-#include "libguile/futures.h"
 #include "libguile/goops.h"
 #include "libguile/hash.h"
 #include "libguile/hashtab.h"
@@ -409,7 +408,6 @@ static const char *const isymnames[] =
   "#@slot-ref",
   "#@slot-set!",
   "#@delay",
-  "#@future",
   "#@call-with-values",
   "#@else",
   "#@arrow",
@@ -784,9 +782,6 @@ static SCM scm_m_do (SCM xorig, SCM env);
 static SCM scm_m_quasiquote (SCM xorig, SCM env);
 static SCM scm_m_delay (SCM xorig, SCM env);
 static SCM scm_m_generalized_set_x (SCM xorig, SCM env);
-#if 0  /* Futures are disabled, see "futures.h".  */
-static SCM scm_m_future (SCM xorig, SCM env);
-#endif
 static SCM scm_m_define (SCM x, SCM env);
 static SCM scm_m_letrec (SCM xorig, SCM env);
 static SCM scm_m_let (SCM xorig, SCM env);
@@ -2196,36 +2191,6 @@ scm_m_eval_when (SCM expr, SCM env SCM_UNUSED)
   return scm_list_1 (SCM_IM_BEGIN);
 }
 
-#if 0
-
-/* See futures.h for a comment why futures are not enabled.
- */
-
-SCM_SYNTAX (s_future, "future", scm_i_makbimacro, scm_m_future);
-SCM_GLOBAL_SYMBOL (scm_sym_future, s_future);
-
-/* Like promises, futures are implemented as closures with an empty
- * parameter list.  Thus, (future <expression>) is transformed into
- * (#@future '() <expression>), where the empty list represents the
- * empty parameter list.  This representation allows for easy creation
- * of the closure during evaluation.  */
-static SCM
-scm_m_future (SCM expr, SCM env)
-{
-  const SCM new_expr = memoize_as_thunk_prototype (expr, env);
-  SCM_SETCAR (new_expr, SCM_IM_FUTURE);
-  return new_expr;
-}
-
-static SCM
-unmemoize_future (const SCM expr, const SCM env)
-{
-  const SCM thunk_expr = SCM_CADDR (expr);
-  return scm_list_2 (scm_sym_future, unmemoize_expression (thunk_expr, env));
-}
-
-#endif /* futures disabled. */
-
 SCM_SYNTAX (s_gset_x, "set!", scm_i_makbimacro, scm_m_generalized_set_x);
 SCM_SYMBOL (scm_sym_setter, "setter");
 
@@ -2494,13 +2459,6 @@ unmemoize_builtin_macro (const SCM expr, const SCM env)
     case (ISYMNUM (SCM_IM_CALL_WITH_VALUES)):
       return unmemoize_at_call_with_values (expr, env);
 
-#if 0
-    /* See futures.h for a comment why futures are not enabled.
-     */
-    case (ISYMNUM (SCM_IM_FUTURE)):
-      return unmemoize_future (expr, env);
-#endif
-
     case (ISYMNUM (SCM_IM_SLOT_REF)):
       return unmemoize_atslot_ref (expr, env);
 
diff --git a/libguile/eval.i.c b/libguile/eval.i.c
index e2e79c2..5e78f6d 100644
--- a/libguile/eval.i.c
+++ b/libguile/eval.i.c
@@ -734,13 +734,6 @@ dispatch:
 	case (ISYMNUM (SCM_IM_DELAY)):
 	  RETURN (scm_make_promise (scm_closure (SCM_CDR (x), env)));
 
-#if 0
-	  /* See futures.h for a comment why futures are not enabled.
-	   */
-	case (ISYMNUM (SCM_IM_FUTURE)):
-	  RETURN (scm_i_make_future (scm_closure (SCM_CDR (x), env)));
-#endif
-
 	  /* PLACEHOLDER for case (ISYMNUM (SCM_IM_DISPATCH)): The following
 	     code (type_dispatch) is intended to be the tail of the case
 	     clause for the internal macro SCM_IM_DISPATCH.  Please don't
diff --git a/libguile/init.c b/libguile/init.c
index 3fbe368..68156ef 100644
--- a/libguile/init.c
+++ b/libguile/init.c
@@ -60,7 +60,6 @@
 #include "libguile/filesys.h"
 #include "libguile/fluids.h"
 #include "libguile/fports.h"
-#include "libguile/futures.h"
 #include "libguile/gc.h"
 #include "libguile/gdbint.h"
 #include "libguile/generalized-arrays.h"
@@ -479,11 +478,6 @@ scm_i_init_guile (SCM_STACKITEM *base)
   scm_init_dynwind ();
   scm_init_eq ();
   scm_init_error ();
-#if 0
-  /* See futures.h for a comment why futures are not enabled.
-   */
-  scm_init_futures ();
-#endif
   scm_init_fluids ();
   scm_init_feature ();          /* Requires fluids */
   scm_init_backtrace ();	/* Requires fluids */
diff --git a/libguile/tags.h b/libguile/tags.h
index 2d14ed2..f745732 100644
--- a/libguile/tags.h
+++ b/libguile/tags.h
@@ -613,7 +613,7 @@ enum scm_tc8_tags
 
 /* Evaluator byte codes ('immediate symbols').  These constants are used only
  * in eval but their values have to be allocated here.  The indices of the
- * SCM_IM_ symbols must agree with the declarations in print.c:
+ * SCM_IM_ symbols must agree with the declarations in eval.c:
  * scm_isymnames.  */
 
 #define SCM_ISYMP(n) 		(SCM_ITAG8 (n) == scm_tc8_isym)
@@ -639,12 +639,11 @@ enum scm_tc8_tags
 #define SCM_IM_SLOT_REF		SCM_MAKISYM (17)
 #define SCM_IM_SLOT_SET_X	SCM_MAKISYM (18)
 #define SCM_IM_DELAY		SCM_MAKISYM (19)
-#define SCM_IM_FUTURE		SCM_MAKISYM (20)
-#define SCM_IM_CALL_WITH_VALUES SCM_MAKISYM (21)
-#define SCM_IM_ELSE             SCM_MAKISYM (22)
-#define SCM_IM_ARROW            SCM_MAKISYM (23)
-#define SCM_IM_NIL_COND         SCM_MAKISYM (24)  /* Multi-language support */
-#define SCM_IM_BIND             SCM_MAKISYM (25)  /* Multi-language support */
+#define SCM_IM_CALL_WITH_VALUES SCM_MAKISYM (20)
+#define SCM_IM_ELSE             SCM_MAKISYM (21)
+#define SCM_IM_ARROW            SCM_MAKISYM (22)
+#define SCM_IM_NIL_COND         SCM_MAKISYM (23)  /* Multi-language support */
+#define SCM_IM_BIND             SCM_MAKISYM (24)  /* Multi-language support */
 
 \f