June 2016 - Haskell-Cafe

Month in Haskell Mode May 2016
by Gracjan Polak 04 Jun '16

04 Jun '16

Hi, Month in Haskell Mode May 2016 progress report is available: https://github.com/haskell/haskell-mode/wiki/Month-in-Haskell-Mode-May-2016 -- Gracjan

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10 open roles in expanding team at Standard Chartered
by Don Stewart 03 Jun '16

03 Jun '16

I have another ten open roles in the growing Strats team at Standard Chartered. https://donsbot.wordpress.com/2016/06/03/multiple-haskell-developer-roles-i… These are full time or contract Haskell developer positions in London or Singapore. Details in the post .

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how to reify an API?
by Johannes Waldmann 02 Jun '16

02 Jun '16

Dear Cafe, I wanted to benchmark (part of) an API of a package, by enumerating all possible (nested) calls by size of their AST, much as smallcheck does it for data. So I made this straightforward AST representation and (generically) got its Serial instances. That last part has been in smallcheck for a long time, and works nicely. But I do wonder if there is a way to get the AST (and corresponding interpreter) with less boilerplate code (than this: https://github.com/jwaldmann/pretty-test/blob/master/src/Lib.hs#L29 ) If you read the code: it also has a type for "AST contexts" because I wanted to iterate them (to produce larger trees). Again - easy to write down, but boring. - J.

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Re: [Haskell-cafe] Is there any way to use somethig like global backtrack with parsec
by Erik Rantapaa 01 Jun '16

01 Jun '16

If don't have to use Parsec, you can use a parser library like ReadP / ReadS. For example: import Text.ParserCombinators.ReadP abc = (choice [ string "a", string "ab" ] ) >> char 'c' >> eof run p s = case (readP_to_S p) s of [] -> Left "no parse" ((a,_):_) -> Right a test1 = run abc "ac" test2 = run abc "abc" test3 = run abc "ab" -- should fail On Monday, May 30, 2016 at 1:15:25 PM UTC-5, Petr Sokolov wrote: > > For example this parser doesn't parse "abc" > > test :: Parser String > test = ((try $ string "a") <|> (string "ab")) *> (string "c") > > I can rewrite it so it would parse "abc", but is there any general > approach to force parser to return and try other branches? > > (try a <|> b) *> c > > Something like > > (tryOtherBranchesIfFail (try a <|> b)) *> c > > So if it cannot parse "abc" with (try a *> c) it could return and try (b > *> c) > Or it isn't possible? > >

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