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2 points by absz 6014 days ago | link | parent

  arc> (given (a b) (list 1 2)
         (pr a b))
  121
The difference between given and let/with is that you cannot have more than one statement in the body of the given. For instance:

  arc> (given (a b) (list 1 2)
         (prn "Here")
         (pr a b))
  Error: "Can't understand fn arg list \"Here\""
What's happening here is that given is trying to bind (prn "Here") to (pr a b), but (naturally) can't bind a string; it takes the first n args, where n is the largest even number less than or equal to the number of arguments provided, and interprets them as variables. You must, therefore, write

  arc> (given (a b) (list 1 2)
         (do
           (prn "Here")
           (pr a b))
  Here
  121
.

Also, I highly recommend switching to Anarki. It's got bugfixes and enhancements galore (and even runs on the newest version of mzscheme).



4 points by bOR_ 6013 days ago | link

So the main drawback of given is that you need to make your do explicit? mmm, I never liked it implicitly anyway ;).

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3 points by absz 6013 days ago | link

It's the only "drawback", if such it is. I feel that since you need extra parentheses for either the body or the variables, it's better to wrap the body in a do, since that's less common.

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