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1 files changed, 14 insertions, 0 deletions

diff --git a/progs/demo/fact.hs b/progs/demo/fact.hs
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--- /dev/null
+++ b/progs/demo/fact.hs
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+{- This is a simple factorial program which uses the I/O system
+   to read the input and print the result -}
+
+module Main where
+
+fact :: Integer -> Integer    
+fact 0 = 1
+fact (n+1) = (n+1)*fact n
+fact _ = error "Negative argument to factorial"
+
+main = appendChan stdout "Type in N: " abort $
+       readChan stdin abort $ \ input ->
+       appendChan stdout (show (fact (read (head (lines input))))) abort done
+