X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=exercises%2Fassignment3.mdwn;h=21997eeb707d2304bc8f08c3545ee8b848a992a2;hp=d1cec2a93c23d719fca2a3b5b2d08eab8fa0d828;hb=14afd28fe72ee04e9accb957cd42686479dc38bb;hpb=077b3c9d4eb81dc63a3b5cf75d4185812728e1f3 diff --git a/exercises/assignment3.mdwn b/exercises/assignment3.mdwn index d1cec2a9..21997eeb 100644 --- a/exercises/assignment3.mdwn +++ b/exercises/assignment3.mdwn @@ -6,7 +6,7 @@ 2. What does `[ 10*x + y | y from [4], x from [1, 2, 3] ]` evalaute to? -3. Using either Kapulet's or Haskell's list comprehension syntax, write an expression that transforms `[3, 1, 0, 2]` into `[3, 3, 3, 1, 2, 2]`. [[Here is a hint|assignment3 hints]], if you need it. +3. Using either Kapulet's or Haskell's list comprehension syntax, write an expression that transforms `[3, 1, 0, 2]` into `[3, 3, 3, 1, 2, 2]`. [[Here is a hint|assignment3 hint1]], if you need it. ## Lists @@ -17,7 +17,7 @@ 6. Continuing to encode lists in terms of their left-folds, what should `last` be, where `last [a, b, c]` should result in `c`. Let `last []` result in whatever `err` is bound to. -7. Continuing to encode lists in terms of their left-folds, how should we write `head`? This is challenging. [[Here is a hint|assignment3 hints]], if you need it. +7. Continuing to encode lists in terms of their left-folds, how should we write `head`? This is challenging. [[Here is a solution|assignment3 hint2]], if you need help. ## Numbers @@ -68,6 +68,25 @@ Using the mapping specified in this week's notes, translate the following lambda 23. For each of the above translations, how many `I`s are there? Give a rule for describing what each `I` corresponds to in the original lambda term. +Evaluation strategies in Combinatory Logic +------------------------------------------ + +23. Find a term in CL that behaves like Omega does in the Lambda +Calculus. Call it Skomega. + +24. Are there evaluation strategies in CL corresponding to leftmost +reduction and rightmost reduction in the lambda calculus? +What counts as a redex in CL? + +25. Consider the CL term K I Skomega. Does leftmost (alternatively, +rightmost) evaluation give results similar to the behavior of K I +Omega in the lambda calculus, or different? What features of the +lambda calculus and CL determine this answer? + +26. What should count as a thunk in CL? What is the equivalent +constraint in CL to forbidding evaluation inside of a lambda abstract? + + More Lambda Practice --------------------