Collapse around hyphen

.github/workflows/sed.sh

@@ -1,7 +1,8 @@
 #!/usr/bin/env bash
 
-sed -e '/^ *$/d'     `# Whitespace-only or empty lines` \
-    -e 's/ / /g'     `# nbsp to space` \
-    -e 's/–/-/g'     `# endash to hyphen` \
-    -e "s/’/'/g"     `# apostrophe to single quote` \
-    -e 's/\s—\s/—/g' `# collapse whitespace around emdash`
+sed -E\
+    -e '/^ *$/d' `# Whitespace-only or empty lines` \
+    -e 's/ / /g' `# nbsp to space` \
+    -e 's/–/-/g' `# endash to hyphen` \
+    -e "s/’/'/g" `# apostrophe to single quote` \
+    -e 's/[[:blank:]]([—-])[[:blank:]]/\1/g' `# collapse whitespace around emdash and hyphen`