Add "selectable exceptions" to $&catch

doc/es.1

@@ -1973,12 +1973,18 @@ 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.
 Signals are blocked during the execution of
 .IR catcher
 and signal exceptions will only be raised after it has finished running.

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
@@ -75,6 +73,7 @@ fn-if		= $&if
 fn-newpgrp	= $&newpgrp
 fn-result	= $&result
 fn-throw	= $&throw
+fn-catch	= $&catch
 fn-umask	= $&umask
 fn-wait		= $&wait
 
@@ -170,10 +169,7 @@ fn var	{ for (i = <={%var $*}) echo $i }
 fn whatis {
 	let (result = ) {
 		for (i = $*) {
-			catch @ e from message {
-				if {!~ $e error} {
-					throw $e $from $message
-				}
+			catch error @ from message {
 				echo >[1=2] $message
 				result = $result 1
 			} {
@@ -190,10 +186,7 @@ fn whatis {
 #	does not catch the return exception.  It does, however, catch break.
 
 fn-while = $&noreturn @ cond body {
-	catch @ e value {
-		if {!~ $e break} {
-			throw $e $value
-		}
+	catch break @ value {
 		result $value
 	} {
 		let (result = <=true)

prim-ctl.c

@@ -47,12 +47,18 @@ PRIM(throw) {
 
 PRIM(catch) {
 	Atomic retry;
+	int argc = length(list);
 
-	if (list == NULL)
-		fail("$&catch", "usage: catch catcher body");
+	if (argc != 2 && argc != 3)
+		fail("$&catch", "usage: catch [exception] catcher body");
 
 	Ref(List *, result, NULL);
 	Ref(List *, lp, list);
+	Ref(char *, exc, NULL);
+	if (argc == 3) {
+		exc = getstr(lp->term);
+		lp = lp->next;
+	}
 
 	do {
 		List *e = NULL;
@@ -62,7 +68,14 @@ PRIM(catch) {
 
 			result = eval(lp->next, NULL, evalflags);
 
-		CatchException (frombody)
+		CatchException (volatile frombody)
+
+			if (exc != NULL) {
+				if (termeq(frombody->term, exc))
+					frombody = frombody->next;
+				else
+					throw(frombody);
+			}
 
 			blocksignals();
 			ExceptionHandler
@@ -89,7 +102,7 @@ PRIM(catch) {
 			throw(e);
 
 	} while (retry);
-	RefEnd(lp);
+	RefEnd2(exc, 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 $*}
 			}