From b500c9bb373fefbf29123d7b5cf47f26b9b7363e Mon Sep 17 00:00:00 2001 From: Jim Pryor Date: Tue, 14 Sep 2010 12:09:06 -0400 Subject: [PATCH] more6 assignment1 tweaks Signed-off-by: Jim Pryor --- assignment1.mdwn | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/assignment1.mdwn b/assignment1.mdwn index 615e1832..fa02cb83 100644 --- a/assignment1.mdwn +++ b/assignment1.mdwn @@ -40,9 +40,7 @@ evaluates to 10.
  • Define an `and` operator. -
  • Define an `xor` operator. - -If you haven't seen this term before, here's a truth table: +
  • Define an `xor` operator. If you haven't seen this term before, here's a truth table: true xor true = false true xor false = true @@ -93,13 +91,11 @@ Now we can write: (p get-first) ; will evaluate to 10 (p get-second) ; will evaluate to 20 -If you're bothered by having the pair to the left and the function that +If you're puzzled by having the pair to the left and the function that operates on it come second, think about why it's being done this way: the pair -is a package that takes a function for operating on its elements as an -argument, and returns the result of operating on its elemens with that -function. In other words, the pair is also a function. (Of course, in the -untyped lambda calculus, absolutely *everything* is a function: functors, -arguments, abstracts, redexes, values---everything.) +is a package that takes a function for operating on its elements *as an +argument*, and returns *the result of* operating on its elements with that +function. In other words, the pair is a higher-order function. (Consider the similarities between this definition of a pair and a generalized quantifier.) If you like, you can disguise what's going on like this: @@ -114,7 +110,7 @@ instead of: (p get-first) -However, the latter is still what's going on under the hood. +However, the latter is still what's going on under the hood. (Remark: `(lifted-f ((make-pair 10) 20))` stands to `(((make-pair 10) 20) f)` as `(((make-pair 10) 20) f)` stands to `((f 10) 20)`.)
      -- 2.11.0