2009/5/6 Bulat Ziganshin <bulat.zigans...@gmail.com>:
Hello applebiz89, Tuesday, May 5, 2009, 7:20:35 PM, you wrote:filmsInGivenYear :: Int -> [Film] -> [String] filmsInGivenYear filmYear ?= [ title | year <- (Film title director year fans) , year == filmYear] (this code wont compile - error given '?Syntax error in expression (unexpected `;', possibly due to bad layout)')you forget films list variable: filmsInGivenYear filmYear films = [ title | (Film title director year fans) <- films, year == filmYear]
And this is nicer if you define Film with records:
-- just guessing as to types
data Film = Film { title :: String, director :: String, year :: Int, fans ::
[Fan] }
filmsInGivenYear filmYear films = [title | film <- films, year film == filmYear]
-- and then it's probably easier written as:
filmsInGivenYear filmYear films = filter (\film -> year film == filmYear) films
-- or slightly simpler:
filmsInGivenYear filmYear = filter (\film -> year film == filmYear)
-- or with Data.Function.Predicate (shameless plug)
<http://hackage.haskell.org/packages/archive/predicates/0.1/doc/html/Data-Function-Predicate.html>:
filmsInGivenYear filmYear = filter (year `equals` filmYear)
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