X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=assignment6.mdwn;h=30763c1a786c93e7ac4d039942a7f69865623849;hp=62d1c5c54366c3e10b6163226b8a2686bfc485be;hb=4c318c7fe4a19f8271864c47459996c8d30fbf99;hpb=1487bf1e23d780ed6abd773c7650115cce1f831a diff --git a/assignment6.mdwn b/assignment6.mdwn index 62d1c5c5..30763c1a 100644 --- a/assignment6.mdwn +++ b/assignment6.mdwn @@ -2,16 +2,17 @@ build a system that will evaluate arithmetic expressions. Instead of returning a simple integer as a result, it will deliver the correct answer along with a count of the number of operations performed during -the calculuation. That is, the desired behavior should be like this: +the calculation. That is, the desired behavior should be like this: - # lift ( + ) (lift ( / ) (unit 20) (unit 2)) (lift ( * ) (unit 2) (unit 3)) 0;; - - : int * int = (16, 3) + # lift2 ( + ) (lift2 ( / ) (unit 20) (unit 2)) + (lift2 ( * ) (unit 2) (unit 3)) 0;; + - : int * int = (16, 3) - Here, `lift` is the function that uses `bind` to prepare an ordinary + Here, `lift2` is the function that uses `bind` to prepare an ordinary arithmetic operator (such as addition `( + )`, division `( / )`, or multiplication `( * )`) to recieve objects from the counting monad as arguments. The response of the interpreter says two things: that -(20/2) + (2*3) = 16, and that the computation took three arithmetic +(20/2) + (2\*3) = 16, and that the computation took three arithmetic steps. By the way, that zero at the end provides the monadic object with a starting point (0 relevant computations have occurred previous to the current computation). @@ -20,8 +21,8 @@ to the current computation). divide by zero (so there should be no int option types anywhere in your solution). - You'll need to define a computation monad type, unit, bind, and lift. -We encourage you to consider this hint: [[Assignment 6 Hint 1]]. + You'll need to define a computation monad type, unit, bind, and lift2. +We encourage you to consider this hint: [[hints/Assignment 6 Hint 1]]. 2. Prove that your monad satisfies the monad laws. First, give examples illustrating specific cases in which the monad laws are