diff --git a/lab01/expo.ml b/labs/01/expo.ml
similarity index 100%
rename from lab01/expo.ml
rename to labs/01/expo.ml
diff --git a/lab01/lab1.ml b/labs/01/lab1.ml
similarity index 100%
rename from lab01/lab1.ml
rename to labs/01/lab1.ml
diff --git a/lab02/lab2.ml b/labs/02/lab2.ml
similarity index 100%
rename from lab02/lab2.ml
rename to labs/02/lab2.ml
diff --git a/lab03/kvtree.ml b/labs/03/kvtree.ml
similarity index 100%
rename from lab03/kvtree.ml
rename to labs/03/kvtree.ml
diff --git a/lab03/part1.ml b/labs/03/part1.ml
similarity index 100%
rename from lab03/part1.ml
rename to labs/03/part1.ml
diff --git a/labs/04/_build/_digests b/labs/04/_build/_digests
new file mode 100644
index 0000000..bc54875
--- /dev/null
+++ b/labs/04/_build/_digests
@@ -0,0 +1,5 @@
+"Rule: ocaml dependencies ml (%=records )": "\168\187\158\232\128I\157\015\216j\244\004\243\234\011\217"
+"Rule: ocaml: ml & cmi -> cmx & o (%=records )": "5\144\205\021B\003\025\204\145\159\255\166t\136\140^"
+"Resource: /home/flami/Projects/comp3958/lab04/records.ml": "\133\242qUUy2\188\b\134=\163c9\2142"
+"Rule: ocaml: ml -> cmo & cmi (%=records )": "\026zi!\193g\255\238<\162\135s\021\142\001\012"
+"Rule: ocaml: cmx* & o* -> native (%=records )": "C\176\141F\181\127\251\240\211V\156\t\167\208\129\177"
diff --git a/labs/04/_build/_log b/labs/04/_build/_log
new file mode 100644
index 0000000..4f9a364
--- /dev/null
+++ b/labs/04/_build/_log
@@ -0,0 +1,12 @@
+### Starting build.
+# Target: /home/flami/.opam/default/bin/ocamlc.opt -config, tags: {  }
+/home/flami/.opam/default/bin/ocamlc.opt -config
+# Target: records.ml.depends, tags: { extension:ml, file:records.ml, ocaml, ocamldep, quiet }
+/home/flami/.opam/default/bin/ocamldep.opt -modules records.ml > records.ml.depends
+# Target: records.cmo, tags: { byte, compile, extension:cmo, extension:ml, file:records.cmo, file:records.ml, implem, ocaml, quiet }
+/home/flami/.opam/default/bin/ocamlc.opt -c -o records.cmo records.ml
+# Target: records.cmx, tags: { compile, extension:cmx, extension:ml, file:records.cmx, file:records.ml, implem, native, ocaml, quiet }
+/home/flami/.opam/default/bin/ocamlopt.opt -c -o records.cmx records.ml
+# Target: records.native, tags: { dont_link_with, extension:native, file:records.native, link, native, ocaml, program, quiet }
+/home/flami/.opam/default/bin/ocamlopt.opt records.cmx -o records.native
+# Compilation successful.
diff --git a/labs/04/_build/records.cmx b/labs/04/_build/records.cmx
new file mode 100644
index 0000000..8fcc2a8
Binary files /dev/null and b/labs/04/_build/records.cmx differ
diff --git a/labs/04/_build/records.ml b/labs/04/_build/records.ml
new file mode 100644
index 0000000..5a7aa97
--- /dev/null
+++ b/labs/04/_build/records.ml
@@ -0,0 +1,143 @@
+(** [record] of a person with a first name, last name, and score *)
+type record = {firstname: string; lastname: string; score: int};;
+
+(** [print_records r] takes a list of records [r] and prints
+  * each record neatly to the console *)
+let rec print_records r =
+  match r with
+  | [] -> ()
+  | x :: xs -> Printf.printf "%3d %s %s\n" x.score x.lastname x.firstname; print_records xs;;
+
+(** [compare_records r1 r2] compares records [r1] and [r2] based
+  * on score, then by lastname, then by firstname.
+  *)
+let compare_records r1 r2 =
+  compare
+    (r2.score, r2.lastname, r2.firstname)
+    (r1.score, r1.lastname, r1.firstname);;
+
+(** [records_insert x l] inserts a record element [x] into
+  * list of records [l]
+  * Requires: [l] is in ascending order. *)
+let rec records_insert x l =
+  match l with
+  | y :: ys when compare_records x y > 0 -> y :: records_insert x ys
+  | _ -> x :: l;;
+
+(**/**)
+let test_records_insert () =
+  assert (records_insert
+    {firstname = "a"; lastname = "b"; score = 1} [] =
+    [{firstname = "a"; lastname = "b"; score = 1}]
+  );
+  assert (records_insert
+    {firstname = "a"; lastname = "b"; score = 1}
+    [{firstname = "c"; lastname = "d"; score = 2}] =
+  [
+    {firstname = "c"; lastname = "d"; score = 2};
+    {firstname = "a"; lastname = "b"; score = 1}
+  ]);
+  assert (records_insert
+    {firstname = "e"; lastname = "f"; score = 2}
+    [
+      {firstname = "c"; lastname = "d"; score = 3};
+      {firstname = "a"; lastname = "b"; score = 1}
+    ] =
+    [
+      {firstname = "c"; lastname = "d"; score = 3};
+      {firstname = "e"; lastname = "f"; score = 2};
+      {firstname = "a"; lastname = "b"; score = 1}
+    ]);;
+(**/**)
+
+(** [records_insertion_sort l] sorts list of records [l] in ascending order *)
+let rec sort_records l =
+  match l with
+  | [] -> []
+  | x :: xs -> records_insert x (sort_records xs);;
+
+(**/**)
+let test_sort_records () =
+  assert (sort_records [] = []);
+  assert (sort_records
+    [{firstname = "a"; lastname = "b"; score = 1}] =
+    [{firstname = "a"; lastname = "b"; score = 1}]);
+
+  assert (sort_records [
+    {firstname = "c"; lastname = "d"; score = 3};
+    {firstname = "a"; lastname = "b"; score = 1};
+    {firstname = "e"; lastname = "f"; score = 2};
+  ] = [
+    {firstname = "c"; lastname = "d"; score = 3};
+    {firstname = "e"; lastname = "f"; score = 2};
+    {firstname = "a"; lastname = "b"; score = 1};
+  ]);;
+(**/**)
+
+(** [parse l] takes in a line [l] and parses the line to extract
+  * firstname, lastname, and score, returning Some record if successful
+  * or None if the input line [l] contains bad data *)
+let rec parse l =
+  try
+    Scanf.sscanf l " %s %s %s" (fun f l s ->
+      match int_of_string_opt s with
+      | Some v when v >= 0 && v <= 100 -> Some {firstname = f; lastname = l; score = v}
+      | _ -> None
+    )
+  with
+  | Scanf.Scan_failure _ -> None;;
+
+(**/**)
+let test_parse () =
+  assert (parse "" = None);
+  assert (parse "Bart simpson 5abc" = None);
+  assert (parse "Lisa simpson 130" = None);
+  assert (parse "Homer Simpson -5" = None);
+  assert (parse "Homer Simpson 5" =
+    Some {firstname = "Homer"; lastname = "Simpson"; score = 5});
+  assert (parse "Homer Simpson 5 blah blah blah" =
+    Some {firstname = "Homer"; lastname = "Simpson"; score = 5});;
+(**/**)
+
+(** [read_file acc ic] takes in an accumulator [acc] and an input channel [ic]
+  * and oterates over it input channel [ic] to parse each line and store the
+  * parsed result into the accumulator [acc] *)
+let rec read_file acc ic =
+  try
+    match parse @@ input_line ic with
+    | None -> read_file acc ic
+    | Some v -> read_file (v :: acc) ic
+  with
+  | End_of_file -> close_in ic; acc;;
+
+(**/**)
+let test_read_file () =
+  assert (read_file [] @@ open_in "data.txt" = [
+    {firstname = "gary"; lastname = "chalmers"; score = 5};
+    {firstname = "waylon"; lastname = "smithers"; score = 100};
+    {firstname = "homer"; lastname = "simpson"; score = 25};
+  ]);
+  assert (read_file [] @@ open_in "data1.txt" = [
+    {firstname = "gary"; lastname = "chalmers"; score = 5};
+    {firstname = "waylon"; lastname = "smithers"; score = 100};
+    {firstname = "ned"; lastname = "flanders"; score = 12};
+    {firstname = "homer"; lastname = "simpson"; score = 25};
+  ]);
+  assert (read_file [] @@ open_in "data2.txt" = []);;
+(**/**)
+
+(**/**)
+let run_all_tests () =
+  test_parse();
+  test_read_file();
+  test_records_insert();
+  test_sort_records();;
+(**/**)
+
+(** main program entry from cli *)
+let () =
+  if Array.length Sys.argv = 1 then
+    Printf.printf "%s: expects 1 file input.\nUsage: \"%s <filename>\"\n" Sys.argv.(0) Sys.argv.(0)
+  else
+    let ic = open_in Sys.argv.(1) in
+    print_records @@ sort_records @@ read_file [] ic;;
diff --git a/labs/04/_build/records.ml.depends b/labs/04/_build/records.ml.depends
new file mode 100644
index 0000000..b0ac031
--- /dev/null
+++ b/labs/04/_build/records.ml.depends
@@ -0,0 +1 @@
+records.ml: Array Printf Scanf Sys
diff --git a/labs/04/_build/records.o b/labs/04/_build/records.o
new file mode 100644
index 0000000..371a671
Binary files /dev/null and b/labs/04/_build/records.o differ
diff --git a/lab04/data.txt b/labs/04/data.txt
similarity index 100%
rename from lab04/data.txt
rename to labs/04/data.txt
diff --git a/lab04/data1.txt b/labs/04/data1.txt
similarity index 100%
rename from lab04/data1.txt
rename to labs/04/data1.txt
diff --git a/lab04/data2.txt b/labs/04/data2.txt
similarity index 100%
rename from lab04/data2.txt
rename to labs/04/data2.txt
diff --git a/lab04/records.ml b/labs/04/records.ml
similarity index 100%
rename from lab04/records.ml
rename to labs/04/records.ml
diff --git a/lab05/kvtree/kvtree.ml b/labs/05/kvtree/kvtree.ml
similarity index 97%
rename from lab05/kvtree/kvtree.ml
rename to labs/05/kvtree/kvtree.ml
index a1e6ea5..aac971f 100644
--- a/lab05/kvtree/kvtree.ml
+++ b/labs/05/kvtree/kvtree.ml
@@ -82,14 +82,14 @@ module Make(Ord: OrderedType) = struct
     match t with
     | L -> L
     | N (k', v, l, r) when Ord.compare k k' < 0 ->
-      N (k', v, delete  k l, r)
+      N (k', v, delete k l, r)
     | N (k', v, l, r) when Ord.compare k k' > 0 ->
-      N (k', v, l, delete  k r)
+      N (k', v, l, delete k r)
     | N (_, _, l, L) -> l
     | N (_, _, L, r) -> r
     | N (_, _, l, r) ->
       let (ks, vs) = largest l in
-      N (ks, vs, delete  ks l, r);;
+      N (ks, vs, delete ks l, r);;
 
   (** [of_list l] takes a list of pairs [l] and creates a
     * kvtree in the order specefied by the comparator [] to compare
diff --git a/lab05/kvtree/kvtree.mli b/labs/05/kvtree/kvtree.mli
similarity index 100%
rename from lab05/kvtree/kvtree.mli
rename to labs/05/kvtree/kvtree.mli
diff --git a/lab05/kvtree/tests.ml b/labs/05/kvtree/tests.ml
similarity index 100%
rename from lab05/kvtree/tests.ml
rename to labs/05/kvtree/tests.ml
diff --git a/lecture01/notes.ml b/lectures/01/notes.ml
similarity index 100%
rename from lecture01/notes.ml
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diff --git a/lecture01/tinker.ml b/lectures/01/tinker.ml
similarity index 100%
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rename to lectures/01/tinker.ml
diff --git a/lecture02/html/Length.html b/lectures/02/html/Length.html
similarity index 100%
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diff --git a/lecture02/html/index.html b/lectures/02/html/index.html
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diff --git a/lecture02/html/index_attributes.html b/lectures/02/html/index_attributes.html
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diff --git a/lecture02/html/index_class_types.html b/lectures/02/html/index_class_types.html
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diff --git a/lecture02/html/index_classes.html b/lectures/02/html/index_classes.html
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diff --git a/lecture02/html/index_exceptions.html b/lectures/02/html/index_exceptions.html
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diff --git a/lecture02/html/index_extensions.html b/lectures/02/html/index_extensions.html
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diff --git a/lecture02/html/index_methods.html b/lectures/02/html/index_methods.html
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diff --git a/lecture02/html/index_module_types.html b/lectures/02/html/index_module_types.html
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diff --git a/lecture02/html/index_modules.html b/lectures/02/html/index_modules.html
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diff --git a/lecture02/html/index_types.html b/lectures/02/html/index_types.html
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rename from lecture02/html/index_types.html
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diff --git a/lecture02/html/index_values.html b/lectures/02/html/index_values.html
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rename from lecture02/html/index_values.html
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diff --git a/lecture02/html/style.css b/lectures/02/html/style.css
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rename from lecture02/html/style.css
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diff --git a/lecture02/html/type_Length.html b/lectures/02/html/type_Length.html
similarity index 100%
rename from lecture02/html/type_Length.html
rename to lectures/02/html/type_Length.html
diff --git a/lecture02/lists.ml b/lectures/02/lists.ml
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diff --git a/lecture02/notes02.ml b/lectures/02/notes02.ml
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diff --git a/lecture03/notes03.ml b/lectures/03/notes03.ml
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diff --git a/lecture04/bstree.ml b/lectures/04/bstree.ml
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diff --git a/lecture04/bstree.mli b/lectures/04/bstree.mli
similarity index 100%
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diff --git a/lecture04/notes.ml b/lectures/04/notes.ml
similarity index 100%
rename from lecture04/notes.ml
rename to lectures/04/notes.ml
diff --git a/lectures/05/_build/_digests b/lectures/05/_build/_digests
new file mode 100644
index 0000000..de7371b
--- /dev/null
+++ b/lectures/05/_build/_digests
@@ -0,0 +1,25 @@
+"Resource: /home/flami/Projects/comp3958/lecture05/number_lines.ml": "n\239\025\\<\011\028#\000A>\249\204\182\170r"
+"Rule: ocaml dependencies ml (%=cat )": "\210V\221`\251\191B\198\232\184\146#\164\015\176,"
+"Rule: ocaml: cmx* & o* -> native (%=number_file_lines )": "R|\021U[G\226zs:\214\154\1910a\177"
+"Rule: ocaml: ml & cmi -> cmx & o (%=cat )": "\025\244\2354\235@{lBk\211\031$\237><"
+"Rule: ocaml: cmx* & o* -> native (%=number_lines )": "\180K\170\211^n:g\196\220\030 \233\127*\149"
+"Rule: ocaml: cmx* & o* -> native (%=echo )": "\196\206\211\186\185&f\154\217p\215\195\248p\1485"
+"Resource: /home/flami/Projects/comp3958/lecture05/echo.ml": "h\001\167\215xe\171\150p\151\004p>\004%\181"
+"Rule: ocaml dependencies ml (%=sum_integers )": "\207\140\220\182.\186\127\200\228\226\152\002dAJ\134"
+"Rule: ocaml dependencies ml (%=echo )": "\237\219\161\187\134\217\180\030\148\240\0166\176W\2222"
+"Resource: /home/flami/Projects/comp3958/lecture05/sum_integers.ml": "#b[\196\162u!\202\205~\135\239\025i\195\215"
+"Rule: ocaml: ml -> cmo & cmi (%=sum_integers )": "\015x\165\015\217\024\189(\143ud\232#\158Um"
+"Rule: ocaml: cmx* & o* -> native (%=sum_integers )": "q.\011\170\190\228da(\218\172\231\192\136\236+"
+"Rule: ocaml: ml -> cmo & cmi (%=cat )": "\248U3\213\015A\001\180 \023\180>\223}\142\188"
+"Rule: ocaml: ml -> cmo & cmi (%=number_file_lines )": "\218\210>\023\150\016u\174\235\179&6\234\147\248\016"
+"Rule: ocaml: ml & cmi -> cmx & o (%=echo )": "\1770\n\142p\235j\205HX\163\208\005\133n\t"
+"Rule: ocaml: ml & cmi -> cmx & o (%=sum_integers )": "\024\022\151\178THu\229\251\017\175G\230\179rD"
+"Rule: ocaml dependencies ml (%=number_lines )": "\023O8\158;\213,z\t`\236\204\250\168\140W"
+"Resource: /home/flami/Projects/comp3958/lecture05/number_file_lines.ml": ":\233\133ai\245 \000\199f8\022\140<\199\174"
+"Resource: /home/flami/Projects/comp3958/lecture05/cat.ml": "^\135\t\199Rr\210]\197\127HpY\r\147\170"
+"Rule: ocaml: ml -> cmo & cmi (%=echo )": "\224\\C\014\150\004=\191p\132*-\017jj\242"
+"Rule: ocaml dependencies ml (%=number_file_lines )": "\142\151\154\251\184\227\201\196\243\150\003\242\017\222\229X"
+"Rule: ocaml: ml & cmi -> cmx & o (%=number_lines )": "l\154\251\180\134\026\206s\139\030!A\155\t\198\161"
+"Rule: ocaml: ml -> cmo & cmi (%=number_lines )": "\029\1849 z\004\n\025\253\155]\017\244\252\141\129"
+"Rule: ocaml: cmx* & o* -> native (%=cat )": "j\019\018\218,\202\215\161 &5SE\134\223/"
+"Rule: ocaml: ml & cmi -> cmx & o (%=number_file_lines )": "|\132>\000@\222\195L,\1271\1424\141wJ"
diff --git a/lectures/05/_build/_log b/lectures/05/_build/_log
new file mode 100644
index 0000000..57df0fc
--- /dev/null
+++ b/lectures/05/_build/_log
@@ -0,0 +1,12 @@
+### Starting build.
+# Target: /home/flami/.opam/default/bin/ocamlc.opt -config, tags: {  }
+/home/flami/.opam/default/bin/ocamlc.opt -config
+# Target: number_lines.ml.depends, tags: { extension:ml, file:number_lines.ml, ocaml, ocamldep, quiet }
+/home/flami/.opam/default/bin/ocamldep.opt -modules number_lines.ml > number_lines.ml.depends
+# Target: number_lines.cmo, tags: { byte, compile, extension:cmo, extension:ml, file:number_lines.cmo, file:number_lines.ml, implem, ocaml, quiet }
+/home/flami/.opam/default/bin/ocamlc.opt -c -o number_lines.cmo number_lines.ml
+# Target: number_lines.cmx, tags: { compile, extension:cmx, extension:ml, file:number_lines.cmx, file:number_lines.ml, implem, native, ocaml, quiet }
+/home/flami/.opam/default/bin/ocamlopt.opt -c -o number_lines.cmx number_lines.ml
+# Target: number_lines.native, tags: { dont_link_with, extension:native, file:number_lines.native, link, native, ocaml, program, quiet }
+/home/flami/.opam/default/bin/ocamlopt.opt number_lines.cmx -o number_lines.native
+# Compilation successful.
diff --git a/lectures/05/_build/cat.cmx b/lectures/05/_build/cat.cmx
new file mode 100644
index 0000000..964d9cd
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diff --git a/lectures/05/_build/cat.ml b/lectures/05/_build/cat.ml
new file mode 100644
index 0000000..0ca6d82
--- /dev/null
+++ b/lectures/05/_build/cat.ml
@@ -0,0 +1,25 @@
+(* display content of file read via stdin *)
+let rec cat () =
+  try
+    let line = read_line () in
+    print_endline line;
+    cat()
+  with
+  | _ -> ();; (* EOF return unit *)
+
+(* similar to main function *)
+let () =
+  let rec aux () =
+    try
+      print_endline @@ read_line ();
+      aux ()
+      with
+      | _ -> ()
+  in
+  aux()
+
+(**** build and test ****)
+(*
+  ocamlbuild cat.native
+  ./cat.native < filename
+*)
diff --git a/lectures/05/_build/cat.ml.depends b/lectures/05/_build/cat.ml.depends
new file mode 100644
index 0000000..832688d
--- /dev/null
+++ b/lectures/05/_build/cat.ml.depends
@@ -0,0 +1 @@
+cat.ml:
diff --git a/lectures/05/_build/cat.o b/lectures/05/_build/cat.o
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diff --git a/lectures/05/_build/echo.cmx b/lectures/05/_build/echo.cmx
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diff --git a/lecture05/echo.ml b/lectures/05/_build/echo.ml
similarity index 100%
rename from lecture05/echo.ml
rename to lectures/05/_build/echo.ml
diff --git a/lectures/05/_build/echo.ml.depends b/lectures/05/_build/echo.ml.depends
new file mode 100644
index 0000000..741a082
--- /dev/null
+++ b/lectures/05/_build/echo.ml.depends
@@ -0,0 +1 @@
+echo.ml: Array Printf Sys
diff --git a/lectures/05/_build/echo.o b/lectures/05/_build/echo.o
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diff --git a/lecture05/number_file_lines.ml b/lectures/05/_build/number_file_lines.ml
similarity index 100%
rename from lecture05/number_file_lines.ml
rename to lectures/05/_build/number_file_lines.ml
diff --git a/lectures/05/_build/number_file_lines.ml.depends b/lectures/05/_build/number_file_lines.ml.depends
new file mode 100644
index 0000000..ae47d2a
--- /dev/null
+++ b/lectures/05/_build/number_file_lines.ml.depends
@@ -0,0 +1 @@
+number_file_lines.ml: Array Printf Sys
diff --git a/lectures/05/_build/number_file_lines.o b/lectures/05/_build/number_file_lines.o
new file mode 100644
index 0000000..498f5ee
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diff --git a/lectures/05/_build/number_lines.cmx b/lectures/05/_build/number_lines.cmx
new file mode 100644
index 0000000..b309989
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diff --git a/lecture05/number_lines.ml b/lectures/05/_build/number_lines.ml
similarity index 100%
rename from lecture05/number_lines.ml
rename to lectures/05/_build/number_lines.ml
diff --git a/lectures/05/_build/number_lines.ml.depends b/lectures/05/_build/number_lines.ml.depends
new file mode 100644
index 0000000..8142677
--- /dev/null
+++ b/lectures/05/_build/number_lines.ml.depends
@@ -0,0 +1 @@
+number_lines.ml: Printf
diff --git a/lectures/05/_build/number_lines.o b/lectures/05/_build/number_lines.o
new file mode 100644
index 0000000..f825a76
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diff --git a/lectures/05/_build/sum_integers.cmx b/lectures/05/_build/sum_integers.cmx
new file mode 100644
index 0000000..f564928
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diff --git a/lecture05/sum_integers.ml b/lectures/05/_build/sum_integers.ml
similarity index 100%
rename from lecture05/sum_integers.ml
rename to lectures/05/_build/sum_integers.ml
diff --git a/lectures/05/_build/sum_integers.ml.depends b/lectures/05/_build/sum_integers.ml.depends
new file mode 100644
index 0000000..55eb6ca
--- /dev/null
+++ b/lectures/05/_build/sum_integers.ml.depends
@@ -0,0 +1 @@
+sum_integers.ml: Printf Scanf
diff --git a/lectures/05/_build/sum_integers.o b/lectures/05/_build/sum_integers.o
new file mode 100644
index 0000000..f8a1a49
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diff --git a/lecture05/cat.ml b/lectures/05/cat.ml
similarity index 100%
rename from lecture05/cat.ml
rename to lectures/05/cat.ml
diff --git a/lecture05/data.txt b/lectures/05/data.txt
similarity index 100%
rename from lecture05/data.txt
rename to lectures/05/data.txt
diff --git a/lectures/05/echo.ml b/lectures/05/echo.ml
new file mode 100644
index 0000000..b2774fd
--- /dev/null
+++ b/lectures/05/echo.ml
@@ -0,0 +1,6 @@
+let () =
+  let len = Array.length Sys.argv - 1 in
+  for i = 1 to len do
+    Printf.printf (if i <> len then "%s " else "%s\n") Sys.argv.(i)
+  done;;
+
diff --git a/lecture05/notes.ml b/lectures/05/notes.ml
similarity index 99%
rename from lecture05/notes.ml
rename to lectures/05/notes.ml
index bdf4153..2711f6e 100644
--- a/lecture05/notes.ml
+++ b/lectures/05/notes.ml
@@ -158,4 +158,3 @@ Scanf.scanf " %d" (fun x -> x)
 (* open_in "filename";; *)
 let ic = open_in "output";;
 input_line ic;;
-
diff --git a/lectures/05/number_file_lines.ml b/lectures/05/number_file_lines.ml
new file mode 100644
index 0000000..477043c
--- /dev/null
+++ b/lectures/05/number_file_lines.ml
@@ -0,0 +1,16 @@
+let rec number acc ic =
+  try
+    Printf.printf "%5d| %s\n" acc @@ input_line ic;
+    number (acc + 1) ic
+  with
+  | _ -> if ic <> stdin then close_in ic else ()
+
+let () =
+  if Array.length Sys.argv = 1 then
+    number 1 stdin
+  else
+    try
+      number 1 @@ open_in Sys.argv.(1)
+    with
+    | Sys_error s -> Printf.eprintf "%s\n" s;;
+
diff --git a/lectures/05/number_lines.ml b/lectures/05/number_lines.ml
new file mode 100644
index 0000000..4028e41
--- /dev/null
+++ b/lectures/05/number_lines.ml
@@ -0,0 +1,9 @@
+let () =
+  let rec aux acc =
+    try
+      Printf.printf "%5d| %s\n" acc @@ read_line ();
+      aux (acc + 1)
+    with
+    | _ -> ()
+  in
+  aux 1;;
diff --git a/lecture05/output b/lectures/05/output
similarity index 100%
rename from lecture05/output
rename to lectures/05/output
diff --git a/lecture05/ref.ml b/lectures/05/ref.ml
similarity index 100%
rename from lecture05/ref.ml
rename to lectures/05/ref.ml
diff --git a/lectures/05/sum_integers.ml b/lectures/05/sum_integers.ml
new file mode 100644
index 0000000..d9b5fac
--- /dev/null
+++ b/lectures/05/sum_integers.ml
@@ -0,0 +1,12 @@
+let () =
+  let rec aux sum =
+    try
+      aux @@ Scanf.scanf " %d" (fun x -> sum + x)
+    with
+    | Scanf.Scan_failure _ ->
+      Scanf.scanf " %s" (fun _ -> ());
+      aux sum
+    | End_of_file -> sum
+  in
+  Printf.printf "%d\n" @@ aux 0;;
+
diff --git a/lectures/06/_build/_digests b/lectures/06/_build/_digests
new file mode 100644
index 0000000..a316040
--- /dev/null
+++ b/lectures/06/_build/_digests
@@ -0,0 +1,3 @@
+"Rule: ocaml dependencies ml (%=two_list_queue )": "\153s\252\225.\205\197\1597\030\142\254Q\213.\135"
+"Resource: /home/flami/Projects/comp3958/lecture06/two_list_queue.ml": "\174\189*\255(\166==\251\006\232\150\141\1714\130"
+"Rule: ocaml: ml -> cmo & cmi (%=two_list_queue )": "9\165\179\031F'#6\127\149\136<\242y\019t"
diff --git a/lectures/06/_build/_log b/lectures/06/_build/_log
new file mode 100644
index 0000000..9d0e2de
--- /dev/null
+++ b/lectures/06/_build/_log
@@ -0,0 +1,8 @@
+### Starting build.
+# Target: /home/flami/.opam/default/bin/ocamlc.opt -config, tags: {  }
+/home/flami/.opam/default/bin/ocamlc.opt -config
+# Target: two_list_queue.ml.depends, tags: { extension:ml, file:two_list_queue.ml, ocaml, ocamldep, quiet }
+/home/flami/.opam/default/bin/ocamldep.opt -modules two_list_queue.ml > two_list_queue.ml.depends
+# Target: two_list_queue.cmo, tags: { byte, compile, extension:cmo, extension:ml, file:two_list_queue.cmo, file:two_list_queue.ml, implem, ocaml, quiet }
+/home/flami/.opam/default/bin/ocamlc.opt -c -o two_list_queue.cmo two_list_queue.ml
+# Compilation successful.
diff --git a/lecture06/two_list_queue.ml b/lectures/06/_build/two_list_queue.ml
similarity index 100%
rename from lecture06/two_list_queue.ml
rename to lectures/06/_build/two_list_queue.ml
diff --git a/lectures/06/_build/two_list_queue.ml.depends b/lectures/06/_build/two_list_queue.ml.depends
new file mode 100644
index 0000000..0d870ba
--- /dev/null
+++ b/lectures/06/_build/two_list_queue.ml.depends
@@ -0,0 +1 @@
+two_list_queue.ml: Fun List
diff --git a/lecture06/bstree.ml b/lectures/06/bstree.ml
similarity index 100%
rename from lecture06/bstree.ml
rename to lectures/06/bstree.ml
diff --git a/lecture06/bstree.mli b/lectures/06/bstree.mli
similarity index 100%
rename from lecture06/bstree.mli
rename to lectures/06/bstree.mli
diff --git a/lecture06/bstree2.ml b/lectures/06/bstree2.ml
similarity index 100%
rename from lecture06/bstree2.ml
rename to lectures/06/bstree2.ml
diff --git a/lecture06/functor/_build/_digests b/lectures/06/functor/_build/_digests
similarity index 100%
rename from lecture06/functor/_build/_digests
rename to lectures/06/functor/_build/_digests
diff --git a/lecture06/functor/_build/_log b/lectures/06/functor/_build/_log
similarity index 100%
rename from lecture06/functor/_build/_log
rename to lectures/06/functor/_build/_log
diff --git a/lecture06/functor/_build/bstree.ml b/lectures/06/functor/_build/bstree.ml
similarity index 100%
rename from lecture06/functor/_build/bstree.ml
rename to lectures/06/functor/_build/bstree.ml
diff --git a/lecture06/functor/_build/bstree.ml.depends b/lectures/06/functor/_build/bstree.ml.depends
similarity index 100%
rename from lecture06/functor/_build/bstree.ml.depends
rename to lectures/06/functor/_build/bstree.ml.depends
diff --git a/lecture06/functor/_build/bstree.mli b/lectures/06/functor/_build/bstree.mli
similarity index 100%
rename from lecture06/functor/_build/bstree.mli
rename to lectures/06/functor/_build/bstree.mli
diff --git a/lecture06/functor/_build/bstree.mli.depends b/lectures/06/functor/_build/bstree.mli.depends
similarity index 100%
rename from lecture06/functor/_build/bstree.mli.depends
rename to lectures/06/functor/_build/bstree.mli.depends
diff --git a/lecture06/functor/bstree.ml b/lectures/06/functor/bstree.ml
similarity index 100%
rename from lecture06/functor/bstree.ml
rename to lectures/06/functor/bstree.ml
diff --git a/lecture06/functor/bstree.mli b/lectures/06/functor/bstree.mli
similarity index 100%
rename from lecture06/functor/bstree.mli
rename to lectures/06/functor/bstree.mli
diff --git a/lecture06/notes.ml b/lectures/06/notes.ml
similarity index 100%
rename from lecture06/notes.ml
rename to lectures/06/notes.ml
diff --git a/lecture06/notes.txt b/lectures/06/notes.txt
similarity index 100%
rename from lecture06/notes.txt
rename to lectures/06/notes.txt
diff --git a/lecture06/queue.ml b/lectures/06/queue.ml
similarity index 100%
rename from lecture06/queue.ml
rename to lectures/06/queue.ml
diff --git a/lectures/06/two_list_queue.ml b/lectures/06/two_list_queue.ml
new file mode 100644
index 0000000..48eff0c
--- /dev/null
+++ b/lectures/06/two_list_queue.ml
@@ -0,0 +1,42 @@
+(* queue is empty iff the first list is empty *)
+type 'a t = 'a list * 'a list;;
+
+exception Empty;;
+
+let empty = ([], []);;
+
+let is_empty (l, _) = l = [];;
+
+let enqueue x (l1, l2) =
+  match l1 with
+  | [] -> [x], l2
+  | _ -> (l1, x :: l2);;
+
+let dequeue (l1, l2) =
+  match l1 with
+  | [] -> raise Empty
+  | [_] -> (List.rev l2, [])
+  | _ :: xs -> (xs, l2);;
+
+let dequeue_opt q =
+  try
+    Some (dequeue q)
+  with
+  | Empty -> None;;
+
+let front (l, _) =
+  match l with
+  | [] -> raise Empty
+  | x :: _ -> x;;
+
+let front_opt (l, _) =
+  match l with
+  | [] -> None
+  | x :: _ -> Some x;;
+
+let of_list l = 
+  List.fold_left (Fun.flip enqueue) empty l;;
+
+let to_list (l1, l2) =
+  l1 @ List.rev l2;;
+
diff --git a/lectures/07/bstree.ml b/lectures/07/bstree.ml
new file mode 100644
index 0000000..83ebf68
--- /dev/null
+++ b/lectures/07/bstree.ml
@@ -0,0 +1,2 @@
+(* bstree with records *)
+type 'a t = L | N of {v: 'a; l: 'a t; r: 'a t};;
diff --git a/lectures/07/counter.ml b/lectures/07/counter.ml
new file mode 100644
index 0000000..402a668
--- /dev/null
+++ b/lectures/07/counter.ml
@@ -0,0 +1,7 @@
+let counter =
+  let c = ref 0 in
+  (fun () -> incr c; !c);;
+
+let make_counter init =
+  let c = ref init in
+  (fun () -> let x = !c in incr c; x);;
diff --git a/lectures/07/frequency.ml b/lectures/07/frequency.ml
new file mode 100644
index 0000000..d00826d
--- /dev/null
+++ b/lectures/07/frequency.ml
@@ -0,0 +1,12 @@
+module F = Map.Make(String)
+
+let rec count map =
+  let word = Scanf.scanf " %s" (fun w -> w) in
+  if word = "" then map
+  else count (F.update word (function
+    | None -> Some 1
+    | Some n -> Some (n + 1))
+  map);;
+
+let () =
+  List.iter (fun (s, n) -> Printf.printf "%s: %d\n" s n) @@ count F.empty;;
diff --git a/lectures/07/leftist.ml b/lectures/07/leftist.ml
new file mode 100644
index 0000000..2ac4afa
--- /dev/null
+++ b/lectures/07/leftist.ml
@@ -0,0 +1,46 @@
+(** rank of node = shortest distance to a leaf (empty node)
+  * hence, rank of node = 1 + min(rnak of left, rank of right)
+  * leftist tree has 2 properties:
+  *  For ever node
+  *  * leftist: rnak(left) >= rank(right)
+  *  * min-heap: value(parent) <= value(node)
+  *)
+
+type 'a t = L | N of int * 'a * 'a t * 'a t;;
+
+exception Empty;;
+
+let rank = function
+  | L -> 0
+  | N (rk, _, _, _) -> rk;;
+
+let empty = L;;
+
+let is_empty t = t = L;;
+
+let rec merge t1 t2 =
+  match t1, t2 with
+  | t, L | L, t -> t
+  | N (_, x1, _, _), N (_, x2, _, _) when x2 < x1 ->
+    merge t2 t1
+  | N (_, x, l, r), t ->
+    let t' = merge r t in
+    if rank t' > rank l then N (1 + rank l, x, t', l)
+    else N (1 + rank t', x, l, t');;
+
+let insert x t =
+  merge t (N (1, x, L, L));;
+
+let of_list l = List.fold_left (Fun.flip insert) L l;;
+
+let get_min = function
+  | L -> raise Empty
+  | N (_, x, _, _) -> x;;
+
+let delete_min = function
+  | L -> L
+  | N (_, _, l, r) -> merge l r;;
+
+let rec to_list t =
+  if is_empty t then []
+  else get_min t :: to_list (delete_min t);;
diff --git a/lectures/07/modules.ml b/lectures/07/modules.ml
new file mode 100644
index 0000000..6ffc1c9
--- /dev/null
+++ b/lectures/07/modules.ml
@@ -0,0 +1,47 @@
+(*
+  - a module can contain other modules as well as module type definitions
+  - a module type/sig (signature) can not contain modules but can contain other sigs
+  - for a .ml/.mli pair,
+    * anything not specified in .mli file is hidden
+    * everything specified in the .mli file must be defined in the .ml file
+*)
+
+module M = struct
+  let f x = 2 * x
+end;;
+
+module type S = module type of M;;
+
+module M = struct
+  let f x = 2 * x;;
+  let g x = 3 * x;;
+  module N = struct
+    type t = int
+  end
+end;;
+
+(* S signature is the same as M if loaded in utop *)
+module type S = module type of M;;
+
+(***** EXTENDED MODULES *****)
+
+(* lets extend List module *)
+module ListExt = struct
+  include List;; (* include module to extend *)
+  let to_array l = Array.of_list l;;
+end;;
+
+ListExt.to_array [3;2;7;6;8];;
+
+module F = Map.Make(String);;
+
+(* returns abstract type *)
+let m = F.empty |> F.add "hello" 1 |> F.add "hello" 2;;
+F.to_list m;;
+
+let incr key m =
+  F.update key (function | None -> Some 1 | Some x -> Some (x + 1))
+  m;;
+
+let m = incr "hello" m;;
+let m = incr "world" m;;
diff --git a/lectures/07/sieve.ml b/lectures/07/sieve.ml
new file mode 100644
index 0000000..0c409b0
--- /dev/null
+++ b/lectures/07/sieve.ml
@@ -0,0 +1,16 @@
+let isqrt n = n |> float_of_int |> sqrt |> int_of_float;;
+
+let sieve n =
+  let is_prime = Array.make n true in
+  for i = 2 to isqrt n do
+    if is_prime.(i) then
+      let j = ref i in
+      while i * !j < n do
+        is_prime.(i * !j) <- false;
+        incr j
+      done
+  done;
+  is_prime.(0) <- false;
+  is_prime.(1) <- false;
+  is_prime |> Array.to_list |> List.mapi (fun i b -> (i, b)) |>
+  List.filter_map (fun (i, b) -> if b then Some i else None);;