From: Taylor R Campbell <campbell@mumble.net>
Date: Mon, 13 Sep 2010 15:28:31 +0000 (+0000)
Subject: New macro BEGIN0.
X-Git-Tag: 20101212-Gtk~57
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=b8a0d136a9a9f97deab9a5d0e8ec199d1351515e;p=mit-scheme.git

New macro BEGIN0.

(BEGIN0 <expression> <command> ...) evaluates <expression>, executes
<command> ..., and then returns the value of <expression>.

(Cf. Common Lisp's PROG1.)
---

diff --git a/src/microcode/uxsig.c b/src/microcode/uxsig.c
index f91c16ee9..eb011b627 100644
--- a/src/microcode/uxsig.c
+++ b/src/microcode/uxsig.c
@@ -549,9 +549,9 @@ DEFUN_STD_HANDLER (sighnd_terminate,
 static
 DEFUN_STD_HANDLER (sighnd_fpe,
 {
+  FPE_RESET_TRAPS ();
   if (executing_scheme_primitive_p ())
     error_floating_point_exception ();
-  FPE_RESET_TRAPS ();
   trap_handler ("floating-point exception", signo, info, scp);
 })
 #endif
diff --git a/src/runtime/mit-macros.scm b/src/runtime/mit-macros.scm
index e142fb39f..98deb9031 100644
--- a/src/runtime/mit-macros.scm
+++ b/src/runtime/mit-macros.scm
@@ -564,4 +564,11 @@ USA.
   `(,keyword:unspecific))
 
 (define (unassigned-expression)
-  `(,keyword:unassigned))
\ No newline at end of file
+  `(,keyword:unassigned))
+
+(define-syntax :begin0
+  (syntax-rules ()
+    ((BEGIN0 form0 form1+ ...)
+     (LET ((RESULT form0))
+       form1+ ...
+       RESULT))))
\ No newline at end of file
diff --git a/src/runtime/runtime.pkg b/src/runtime/runtime.pkg
index 47fa4d19b..390d57e7b 100644
--- a/src/runtime/runtime.pkg
+++ b/src/runtime/runtime.pkg
@@ -4599,6 +4599,7 @@ USA.
 	  (access :access)
 	  (and :and)
 	  (and-let* :and-let*)
+	  (begin0 :begin0)
 	  (case :case)
 	  (cond :cond)
 	  (cond-expand :cond-expand)