fragamus

I installed stack 1.9.3 x86_64 hpack-0.31.2


I tried to test it out like this but it failed:

542be632325c:/# stack new funny new-template -p "author-name:blah" -p "category:blah" -p "copyright:blah" -p "github-username:blah" -p "author-email:blah@blah.com"
Downloading template "new-template" to create project "funny" in funny/ ...
Looking for .cabal or package.yaml files to use to init the project.
Using cabal packages:
- funny/

fragamus

RUN git clone --branch ghc-8.4 https://github.com/ghcjs/ghcjs.git
WORKDIR ghcjs
RUN git submodule update --init --recursive
RUN ./utils/makePackages.sh
RUN ./utils/makeSandbox.sh
RUN cabal install
ENV PATH /ghcjs/.cabal-sandbox/bin:$PATH
WORKDIR  /
RUN ghcjs-boot -v2
RUN /ghcjs/utils/makePackages.sh

fragamus

Error: While constructing the build plan, the following exceptions were encountered:

In the dependencies for twi-0.1.0.0:
    template-haskell-2.11.1.0 from stack configuration does not match >=2.14.0.0  (latest
                              matching version is 2.14.0.0)
needed since twi is a build target.

Some different approaches to resolving this:

  * Set 'allow-newer: true'

fragamus

NOTE: the types used below, e.g. Name or UnQual come from Language.Haskell.Exts

I am using generic-lens to do this kind of traversal:

putStrLn $ show $ toListOf (types @(Name SrcSpanInfo)) foo


When foo is this expression it works fine:

(UnQual (SrcSpanInfo {srcInfoSpan = SrcSpan "Syntax.hs" 268 24 268 32, srcInfoPoints = []}) 

fragamus

This code:

toListOf (types @(Name SrcSpanInfo))
         $ (TyCon
              (SrcSpanInfo
                 {srcInfoSpan = SrcSpan "Foo.hs" 268 24 268 32,
                  srcInfoPoints = []})
              (UnQual
                 (SrcSpanInfo
                    {srcInfoSpan = SrcSpan "Foo.hs" 268 24 268 32,

fragamus

data Module l
    = Module l (Maybe (ModuleHead l)) [ModulePragma l] [ImportDecl l] [Decl l]
    -- ^ an ordinary Haskell module
    | XmlPage l (ModuleName l) [ModulePragma l] (XName l) [XAttr l] (Maybe (Exp l)) [Exp l]
    -- ^ a module consisting of a single XML document. The ModuleName never appears in the source
    --   but is needed for semantic purposes, it will be the same as the file name.
    | XmlHybrid l (Maybe (ModuleHead l)) [ModulePragma l] [ImportDecl l] [Decl l]
                (XName l) [XAttr l] (Maybe (Exp l)) [Exp l]
    -- ^ a hybrid module combining an XML document with an ordinary module
  deriving (Eq,Ord,Show,Typeable,Data,Foldable,Traversable,Functor,Generic)

fragamus

I am using generic lens to access this algebraic data type's elements by position. It works for position 1 and fails for position 2.

    putStrLn $ show $ ast ^. position @1
    putStrLn $ show $ ast ^. position @2

Here's the algebraic data type:

data Module l
    = Module l (Maybe (ModuleHead l)) [ModulePragma l] [ImportDecl l] [Decl l]

fragamus

public static String pingPongBallToStringThatIsBothMachineReadableAndHumanReadable(PingPongBall a){
            Function<PingPongBall,byte[]> funky = x -> x.toByteArray();
            return funky
                .andThen(x->Base64.getEncoder().encode(x))
                .andThen(x->x+"\n"+a)
                .apply(a);
        }

fragamus

data Store s a = Schmore (s -> a) s deriving Functor

instance Comonad (Store s) where
  extract (Schmore f s) = f s
  duplicate (Schmore f s) = Schmore (Schmore f) s

fragamus

data Store s a = Store (s -> a) s deriving Functor

instance Comonad (Store s) where
  extract (Store f s) = f s
  duplicate (Store f s) = Store (Store f) s