Data commit

Task/String-matching/Lambdatalk/string-matching.lambdatalk

@@ -0,0 +1,43 @@
+{def S.in
+ {def S.in.r {lambda {:c :w :i :n}
+  {if {= :i :n}
+   then -1
+   else {if {W.equal? :c {W.get :i :w}}
+   then :i
+   else {S.in.r :c :w {+ :i 1} :n}}}}}
+ {lambda {:c :w}
+  {S.in.r :c :w 0 {W.length :w}}}}
+-> S.in
+
+
+
+{def startswith
+ {lambda {:w1 :w2}
+  {= {S.in _ {S.replace :w2 by _ in :w1}} 0}}}
+-> startswith
+
+{def endswith
+ {lambda {:w1 :w2}
+  {= {S.in _ {S.replace :w2 by _ in :w1}}
+     {- {W.length :w1} {W.length :w2}}}}}
+-> endswith
+
+{def isin
+ {lambda {:w1 :w2}
+  {S.in _ {S.replace :w2 by _ in :w1}}}}
+-> isin
+
+{startswith nabuchodonosor nabu}
+-> true
+{startswith nabuchodonosor abu}
+-> false
+
+{endswith nabuchodonosor sor}
+-> true
+{endswith nabuchodonosor oso}
+-> false
+
+{isin nabuchodonosor oso}
+-> 10   // is in at 10
+{isin nabuchodonosor xyz}
+-> -1   // is not in