sec02 worksheet

section/sec02/sec02.ml

+(* Section 02 worksheet *)
+
+(** Recursion and non-recursion practice *)
+
+(* Write a function increment_all of type int list -> int list that adds one to
+   all the elements of the input list. *)
+(* YOUR BINDING HERE *)
+
+(* Using these functions from lecture, write another implementation of
+   sum_of_first_n_ints that is not itself recursive, but only calls other
+   functions. *)
+
+let rec countdown((n: int)) =
+  if n = 0
+  then []
+  else n :: countdown(n-1)
+
+let rec sum((l: int list)) =
+  if l = []
+  then 0
+  else List.hd(l) + sum(List.tl(l))
+
+(* YOUR BINDING HERE *)
+
+(** Shadowing practice *)
+
+let a = 1
+let b = 2 + a
+let a = "hi"
+let c = b + 1
+
+(* What does this code do? Does it typecheck? What values does each variable have? *)
+
+(** Practice with triples *)
+
+let fst3 (x,_,_) = x (* gets the first element of a triple *)
+let snd3 (_,x,_) = x (* gets the second element of a triple *)
+let thd3 (_,_,x) = x (* gets the third element of a triple *)
+
+(* Write a function that takes two int triples (i.e., two arguments of type "int
+   * int * int") and returns whether the third component of the first argument
+   is equal to the first component of the second argument. *)
+(* YOUR BINDING HERE *)
+
+
+(* Write a function firsts3 that takes an (int * int * int) list and returns an
+   int list consisting of just the first components of all the triples in the
+   input list.
+
+   Hint: Similar to firsts from lec03.ml
+*)
+(* YOUR BINDING HERE *)
+
+(** Debugging practice *)
+
+(* The code below has several errors in it so we can try to debug them.
+   Uncomment it, then fix the errors. *)
+
+(*
+
+let x = 34
+
+y = x + 1
+
+let z = if y then 34 else x < 4
+
+let q = if y > 0 then 0
+
+let w = 0
+
+let let = 34
+
+let v = 4.0 / 2.0
+
+let u = x / w
+
+let 0cse341 = true
+
+*)