May 2019 - Beginners - Haskell.org

Where is my stack ghci?
by Lawrence Bottorff 28 May '19

28 May '19

I've installed Haskell the stack way, but a > which ghc or > whcih ghci comes up with nothing. How can I tell my (Ubuntu 19.04) system where to find ghci? LB

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Emacs org-mode code block problem
by Lawrence Bottorff 27 May '19

27 May '19

I've got this in an Emacs org-mode code block: #+begin_src haskell :results output doubleSmallNumber4 x = if x > 0 then x else x * 2 #+end_src but when I try to run it (with C-c C-c) I get ... Prelude> doubleSmallNumber4 x = if x > 0 then x else x * 2 "org-babel-haskell-eoe" <interactive>:19:23: error: parse error (possibly incorrect indentation or mismatched brackets) Prelude> <interactive>:20:11: error: parse error (possibly incorrect indentation or mismatched brackets) Prelude> <interactive>:21:5-8: error: parse error on input ‘then’ Prelude> <interactive>:22:5-8: error: parse error on input ‘else’ Prelude> "org-babel-haskell-eoe" ... I can run #+begin_src haskell tripleMe x = x + x + x #+end_src just fine though -- which means I've done something right with my Emacs init. The REPL started is 8.6.3 stack-ghci. I've formatted with the org-mode C-c ' LB

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Common Method for [Maybe a] -> [a]
by Leonhard Applis 03 May '19

03 May '19

Hey there, I've got a method: demaybefy :: [Maybe a] -> [a] demaybefy [] = [] demaybefy (x:xs) = case x of Just x -> x : demaybefy xs Nothing -> demaybefy xs However, i feel that there is a method from preload/list/maybe that does exactly the same, but i cannot find it. Can someone help me? best regards Leonhard

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