ISBN13 check digit: Difference between revisions

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 =={{header|langur}}==
 {{works with|langur|0.7.1}}
+In this example, we map to multiple functions (actually 1 no-op).
 <lang langur>val .isbn13checkdigit = f(var .s) {
     matching(re/^[0-9]{13}$/, .s = replace(.s, RE/[\- ]/)) and
         fold(f{+}, map([_, f .d x 3], map(f .c-'0', s2cp .s))) rem 10 == 0
+}
+val .tests = h{
+    "978-1734314502": true,
+    "978-1734314509": false,
+    "978-1788399081": true,
+    "978-1788399083": false,
+}
+for .key in sort(keys .tests) {
+    val .pass = .isbn13checkdigit(.key)
+    write .key, ": ", if(.pass: "good"; "bad")
+    writeln if(.pass == .tests[.key]: ""; " (ISBN-13 CHECK DIGIT TEST FAILED)")
+}</lang>
+{{works with|langur|0.7.0}}
+In this example, we set a for loop value as it progresses.
+<lang langur>val .isbn13checkdigit = f(var .s) {
+    var .odd = true
+    matching(re/^[0-9]{13}$/, .s = replace(.s, RE/[\- ]/)) and
+        for[=0] .d in map(f .c-'0', s2cp .s) { _for += if(.odd: .d; .d x 3); .odd = not .odd } rem 10 == 0
 }