Add "selectable exceptions" to $&catch

doc/es.1

@@ -1959,12 +1959,18 @@ Exits the current loop.
 .I Value
 is used as the return value for the loop command.
 .TP
-.Cr "catch \fIcatcher body\fP"
+.Cr "catch \fR[\fP\fIexception\fP\fR]\fP \fIcatcher body\fP"
 Runs
 .IR body .
-If it raises an exception,
+If it raises an exception, and
+.IR exception
+is either not provided or matches the first term of the exception,
 .IR catcher
 is run and passed the exception as an argument.
+If
+.IR exception
+is provided, then the passed argument does not include the first term
+of the exception, which has already been matched.
 .TP
 .Cr "cd \fR[\fP\fIdirectory\fP\fR]\fP"
 Changes the current directory to

initial.es

@@ -65,8 +65,6 @@
 
 fn-.		= $&dot
 fn-access	= $&access
-fn-break	= $&break
-fn-catch	= $&catch
 fn-echo		= $&echo
 fn-exec		= $&exec
 fn-forever	= $&forever
@@ -102,6 +100,30 @@ fn-break	= throw break
 fn-exit		= throw exit
 fn-return	= throw return
 
+#	The catch function wraps $&catch and adds handling for "selectable
+#	exceptions": if catch is called like `catch foo $catcher $body`, then
+#	`catch` will only actually catch the 'foo' exception, and no others.
+
+fn-catch = $&noreturn @ catcher body {
+	let (exception = ()) {
+		if {!~ $#body (0 1)} {
+			(exception catcher body) = $catcher $body
+		}
+		if {!~ $#body (0 1)} {
+			throw error catch 'usage: catch [exception] catcher body'
+		}
+		$&catch @ e rest {
+			if {~ $#exception 0} {
+				$&noreturn $catcher $e $rest
+			} {~ $exception $e} {
+				$&noreturn $catcher $rest
+			} {
+				throw $e $rest
+			}
+		} $body
+	}
+}
+
 #	unwind-protect is a simple wrapper around catch that is used
 #	to ensure that some cleanup code is run after running a code
 #	fragment.  This function must be written with care to make

prim-ctl.c

@@ -86,6 +86,7 @@ PRIM(catch) {
 
 		SIGCHK();
 	} while (retry);
+	SIGCHK();
 	RefEnd(lp);
 	RefReturn(result);
 }

share/path-cache.es

@@ -58,12 +58,8 @@ fn recache progs {
 fn precache progs {
 	let (result = ())
 	for (p = $progs) {
-		catch @ e type msg {
-			if {~ $e error} {
-				echo >[1=2] $msg
-			} {
-				throw $e $type $msg
-			}
+		catch error @ _ msg {
+			echo >[1=2] $msg
 		} {
 			result = $result <={%pathsearch $p}
 		}

share/status.es

@@ -20,11 +20,9 @@ fn %interactive-loop {
 		noexport = $noexport status
 		status = <=true
 		fn-%dispatch = $&noreturn @ {
-			catch @ e rest {
-				if {~ $e return} {
-					status = $rest
-				}
-				throw $e $rest
+			catch return @ value {
+				status = $value
+				return $value
 			} {
 				status = <={$d $*}
 			}