haskell: Clean up README
This commit is contained in:
Eivind Fonn
parent
df669900da
commit
3145e70f72
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@ -24,28 +24,28 @@
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- [[Cabal commands][Cabal commands]]
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- [[Cabal files][Cabal files]]
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- [[Ghc-mod][Ghc-mod]]
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- [[insert template][insert template]]
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- [[Insert template][Insert template]]
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- [[Syntax checking][Syntax checking]]
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- [[Flycheck ][Flycheck ]]
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- [[HLint][HLint]]
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- [[ghc-mod][ghc-mod]]
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- [[Haskell-mode interactive][Haskell-mode interactive]]
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- [[Interactive haskell-mode][Interactive haskell-mode]]
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- [[Flymake][Flymake]]
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- [[Troubles shooting][Troubles shooting]]
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- [[Troublesshooting][Troublesshooting]]
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- [[FAQ][FAQ]]
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- [[REPL doesn't work][REPL doesn't work]]
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- [[REPL is stuck][REPL is stuck]]
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- [[The REPL doesn't work][The REPL doesn't work]]
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- [[The REPL is stuck][The REPL is stuck]]
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- [[I am using =stack= and =ghc-mod=, but =ghc-mod= doesn't work][I am using =stack= and =ghc-mod=, but =ghc-mod= doesn't work]]
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- [[Indentation doesn't reset when pressing return after empty line][Indentation doesn't reset when pressing return after empty line]]
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- [[Indentation doesn't reset when pressing return after an empty line][Indentation doesn't reset when pressing return after an empty line]]
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- [[Flycheck displays HLInt warnings but not errors][Flycheck displays HLInt warnings but not errors]]
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- [[I can see highlighted errors but they don't appear in the errors list][I can see highlighted errors but they don't appear in the errors list]]
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- [[I can see highlighted errors but they don't appear in the error list][I can see highlighted errors but they don't appear in the error list]]
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- [[Flycheck doesn't work][Flycheck doesn't work]]
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- [[Flycheck doesn't work with =stack=][Flycheck doesn't work with =stack=]]
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- [[stack build directory is wrong][stack build directory is wrong]]
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- [[Project root directory not set properly][Project root directory not set properly]]
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- [[The stack build directory is wrong][The stack build directory is wrong]]
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- [[The Project root directory is not set properly][The Project root directory is not set properly]]
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- [[haskell-mode commands don't work ][haskell-mode commands don't work ]]
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- [[=ghc-mod= and =haskell-mode= commands overlaps. How do I know which command belongs to what ?][=ghc-mod= and =haskell-mode= commands overlaps. How do I know which command belongs to what ?]]
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- [[Some commands start with =ghc-= and some with =haskell-=. What does that mean ?][Some commands start with =ghc-= and some with =haskell-=. What does that mean ?]]
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- [[=ghc-mod= and =haskell-mode= commands overlap. How do I know which command belongs to what?][=ghc-mod= and =haskell-mode= commands overlap. How do I know which command belongs to what?]]
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- [[Some commands start with =ghc-= and some with =haskell-=. What does that mean?][Some commands start with =ghc-= and some with =haskell-=. What does that mean?]]
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* Description
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This layer adds support for the [[https://www.haskell.org/][Haskell]] language.
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@ -108,9 +108,8 @@ the project root. As it will confuse =ghc-mod=. For more troubleshooting,
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checkout this [[https://github.com/kazu-yamamoto/ghc-mod/wiki#known-issues-related-to-stack][document]].
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*** Stack users
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Time to time =ghc-mod= is not available via latest Stackage LTS version. So if
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you have problems with calling =stack install ghc-mod=, try to use =stack
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From time to time =ghc-mod= is not available via latest Stackage LTS version. So
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if you have problems with calling =stack install ghc-mod=, try to use =stack
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install ghc-mod --resolver lts-3.1= (the last known LTS version that had
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=ghc-mod=). But even if it doesn't work, don't panic, it's easy to install it
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from sources.
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@ -143,23 +142,23 @@ $ rm -rf ghc-mod
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#+END_SRC
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** Optional extras
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The Haskell layer supports some extra features that can be enabled through
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layer variables.
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The Haskell layer supports some extra features that can be enabled through layer
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variables.
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*** GHCi-ng support
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[[https://github.com/chrisdone/ghci-ng][ghci-ng]] adds some nice features to =haskell-mode=, and is supported in
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Spacemacs by a layer variable:
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[[https://github.com/chrisdone/ghci-ng][ghci-ng]] adds some nice features to =haskell-mode=, and is supported in Spacemacs
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by a layer variable:
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Follow the instructions to install [[https://github.com/chrisdone/ghci-ng][ghci-ng]] (remember to add =:set +c=
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in =~/.ghci=), next set the layer variable:
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Follow the instructions to install [[https://github.com/chrisdone/ghci-ng][ghci-ng]] (remember to add =:set +c= in
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=~/.ghci=), next set the layer variable:
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#+BEGIN_SRC emacs-lisp
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(setq-default dotspacemacs-configuration-layers
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'((haskell :variables haskell-enable-ghci-ng-support t)))
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#+END_SRC
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Once ghci-ng is enabled, two of the old keybindings are overriden with
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improved versions from ghci-ng, and a new keybinding available:
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Once ghci-ng is enabled, two of the old keybindings are overriden with improved
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versions from ghci-ng, and a new keybinding available:
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| Key Binding | Description |
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|-------------+---------------------------------------------------------------------------|
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@ -168,7 +167,6 @@ improved versions from ghci-ng, and a new keybinding available:
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| ~SPC m u~ | finds uses of identifier |
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**** Stack users
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=Stack= and =ghci-ng= doesn't play well with each other, so the general advice
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is to avoid mixing them. But, if you want mix them anyway, you'll need to set
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=haskell-process-type= explicitly:
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@ -186,8 +184,7 @@ if you have =stack.yaml= file in the root of your project, =stack-ghci= will be
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used as process type.
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**** ghc-mod users
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If you want to use ~SPC m h t~ from =ghc-mod= instead of =ghci-ng= - then you
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If you want to use ~SPC m h t~ from =ghc-mod= instead of =ghci-ng=, then you
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need to add following line in your =dotspacemacs/user-config=:
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#+BEGIN_SRC emacs-lisp
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@ -199,8 +196,8 @@ This might be useful, because =ghc-mod= doesn't require active REPL in order to
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get type of symbol.
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*** structured-haskell-mode
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[[https://github.com/chrisdone/structured-haskell-mode][structured-haskell-mode]], or shm, replaces default haskell-mode
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auto-indentation and adds some nice functionalities.
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[[https://github.com/chrisdone/structured-haskell-mode][structured-haskell-mode]], or shm, replaces default haskell-mode auto-indentation
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and adds some nice functionalities.
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To install =shm= run =cabal install structured-haskell-mode= (or =stack=
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equivalent).
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@ -226,22 +223,22 @@ For a nice visualization of these functions, please refer to the github page
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for [[https://github.com/chrisdone/structured-haskell-mode#features][structured-haskell-mode]].
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*Warning* structured-haskell-mode doesn't play very well with =evil=
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([[https://github.com/chrisdone/structured-haskell-mode/issues/81][structured-haskell-mode/#81]]). So it's better to be used with =emacs= edit
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style.
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([[https://github.com/chrisdone/structured-haskell-mode/issues/81][structured-haskell-mode/#81]]). So it's recommended only to be used with the
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=emacs= editing style.
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*** hindent
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[[https://github.com/chrisdone/hindent][hindent]] is an extensible Haskell pretty printer, which let's you
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reformat your code. You need to install the executable with =cabal
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install hindent= or =stack install hindent=
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To enable it you have to set the variable =haskell-enable-hindent-style=
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to a supported style. The available styles are:
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To enable it you have to set the variable =haskell-enable-hindent-style= to a
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supported style. The available styles are:
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- fundamental
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- johan-tibell
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- chris-done
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- gibiansky
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See examples [[https://github.com/chrisdone/hindent#example][here]]
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See examples [[https://github.com/chrisdone/hindent#example][here]].
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#+BEGIN_SRC emacs-lisp
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(setq-default dotspacemacs-configuration-layers
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@ -349,59 +346,66 @@ ghc-mod commands are prefixed by ~SPC m m~:
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| ~SPC m m >~ | make indent deeper |
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| ~SPC m m <~ | make indent shallower |
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*** insert template
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~SPC m m t~ inserts a template. What this means is that
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In the beginning of a buffer, "module Foo where" is
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inserted. On the function without signature, inferred
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type is inserted. On a symbol "foo" without definition,
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"foo = undefined" is inserted or a proper module is imported.
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~SPC m m u~ inserts a hole in this case. On a variable,
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the case is split. When checking with hlint, original code
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is replaced with hlint's suggestion if possible.
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*** Insert template
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~SPC m m t~ inserts a template. What this means is that in the beginning of a
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buffer, =module Foo where= is inserted. On a function without signature, the
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inferred type is inserted. On a symbol =foo= without definition, =foo =
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undefined= is inserted or a proper module is imported. ~SPC m m u~ inserts a
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hole in this case. On a variable, the case is split. When checking with hlint,
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original code is replaced with hlint's suggestion if possible.
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* Syntax checking
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At the moment there are 4 components which can check the syntax and indicates somehow error and warnings in the code.
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Those components are :
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At the moment there are four components which can check the syntax and indicates
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somehow error and warnings in the code. Those components are
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- flycheck
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- hlint (via flycheck)
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- ghc-mod
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- haskell-mode interactive
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- flycheck
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- hlint (via flycheck)
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- ghc-mod
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- haskell-mode interactive
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As all those components can be active at the same time, it can be tricky to know which component is display which message,
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especially when they disagree or one is not working. Only flycheck errors (ghc and hlint) are displayed in the error list and
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can be navigated using the standard spacemacs key bindings even though errors from other mode might highlight error in the buffer.
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As all these components can be active at the same time, it can be tricky to know
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which component is displaying which message, especially when they disagree or
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one is not working. Only flycheck errors (ghc and hlint) are displayed in the
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error list and can be navigated using the standard spacemacs key bindings (under
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~SPC e~) even though errors from other modes might highlight the actual buffer.
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** Flycheck
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This is the standard spacemacs way to do syntax checking and the most elaborate. flyckeck displays errors, warning, info, including symbols on the left or right side of the buffer
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and tooltips if possible.
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Errors are also available in the error window (~SPC e l~) and you can navigate between errors using ~SPC e n~ and ~SPC e p~.
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Flycheck can be toggle on/off with ~SPC t s~.
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Flycheck has different haskell checker : haskell-ghc, haskell-stackghc and haskell-hlint.
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It normally detect automatically the good one, but if it doesn't work, you can change it using =flycheck-select-checker= (~SPC e s~).
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This is the standard spacemacs way to do syntax checking and the most elaborate.
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You need the syntax-checking layer to enable this. Please the documentation for
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that layer on how to interact with flycheck.
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Flycheck has different Haskell checkers: =haskell-ghc=, =haskell-stackghc= and
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=haskell-hlint=. Normally it can automatically detect the best one to use, but
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if it doesn't work, you can change it using ~SPC e s~.
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** HLint
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HLint is a linter for Haskell. It doesn't detect error (as long as it can parse the file) but detect bad coding style and code smell.
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HLint checker is called *after* the flycheck ghc checker.
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HLint is a linter for Haskell. It doesn't detect errors (as long as it can parse
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the file) but bad coding style and code smell. The HLint checker is called
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*after* the flycheck GHC checker.
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** ghc-mod
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ghc-mod when enabled, does also syntax checking. It doesn't highlight errors but instead displays a ! in the left band.
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You can navigate between errors using =ghc-goto-next-error= (~M-n)~ and =ghc-goto-prev-error= (~M-p~).
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** Haskell-mode interactive
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Finally, haskell-mode when in interactive (~SPC m s b~) also displays errors.
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haskell-mode errors can be navigated from the interactive buffer (by clicking on the error) or using
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=haskell-goto-next-error= (~M-n~) and =haskell-goto-prev-error= (~M-p~) (same binding as ghc-mod).
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Ghc-mod, when enabled, also does syntax checking. It doesn't highlight errors
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but instead displays an exclamation point in the fringe. You can navigate
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between errors using =ghc-goto-next-error= (~M-n~) and =ghc-goto-prev-error=
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(~M-p~).
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** Interactive haskell-mode
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Finally, interactive haskell-mode (~SPC m s b~) also displays errors. These
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errors can be navigated from the interactive buffer (by clicking on the error)
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or using =haskell-goto-next-error= (~M-n~) and =haskell-goto-prev-error=
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(~M-p~).
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** Flymake
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An alternative to syntax checking is to build your project using =flymake-compile=. It doesn't highlight the error on the buffer but is more reliable.
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Error navigation is similar to haskell-mode interactive.
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** Troubles shooting
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Flycheck and ghc-mod can fails silently for miscellaneous reasons. See the [[FAQ]] for trouble shootings.
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An alternative to syntax checking is to build your project using
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=flymake-compile=. It doesn't highlight error in the buffer but is more
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reliable. The error navigation is similar to interactive haskell-mode.
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** Troublesshooting
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Flycheck and ghc-mod can fail silently for miscellaneous reasons. See the [[FAQ]]
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for troubleshooting.
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* FAQ
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** REPL doesn't work
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** The REPL doesn't work
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Usually =haskell-mode= is great at figuring out which interactive process to
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bring up. But if you are experiencing problems with it you can help
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=haskell-mode= by setting =haskell-process-type= as in following code:
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@ -419,7 +423,7 @@ Available options are:
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- cabal-ghci
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- stack-ghci
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** REPL is stuck
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** The REPL is stuck
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Make sure that when you are typing anything in REPL there is a space between
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what you type and =λ>=. When there is no space - REPL will behave as it's stuck.
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Usually, when you enter normal state, cursor is moved back, so there is no
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@ -450,9 +454,11 @@ could place following snippet in your =dotspacemacs/user-config= function:
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** I am using =stack= and =ghc-mod=, but =ghc-mod= doesn't work
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Make sure that =dist= directory doesn't exist in your project root. So if it
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exists, just remove it and try again.
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** Indentation doesn't reset when pressing return after empty line
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This is intended behavior in =haskell-indentation-mode=. If you want to reset indentation when pressing return after empty line, add following snippet into your =dotspacemacs/user-config= function.
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** Indentation doesn't reset when pressing return after an empty line
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This is the intended behavior in =haskell-indentation-mode=. If you want to
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reset indentation when pressing return after an empty line, add the following
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snippet into your =dotspacemacs/user-config= function.
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#+BEGIN_SRC emacs-lisp
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(defun haskell-indentation-advice ()
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@ -465,45 +471,54 @@ This is intended behavior in =haskell-indentation-mode=. If you want to reset in
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(advice-add 'haskell-indentation-newline-and-indent
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:after 'haskell-indentation-advice)
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#+END_SRC
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** Flycheck displays HLInt warnings but not errors
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HLint checker is called *after* normal flycheck checker even if the checkers fails. Check the [[Flycheck doesn't work]] section.
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** I can see highlighted errors but they don't appear in the errors list
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The errors list is only set by flycheck. You are probably seeing highlightings coming from either ghc-mode or haskell-mode.
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Check the [[Flycheck doesn't work]] section.
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The HLint checker is called *after* normal flycheck checker even if the checker
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fails. Check the [[Flycheck doesn't work]] section.
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** I can see highlighted errors but they don't appear in the error list
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The error list is only set by flycheck. You are probably seeing errors
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highlighted by either ghc-mode or haskell-mode. Check the [[Flycheck doesn't work]]
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section.
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** Flycheck doesn't work
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You can check what is wrong with flycheck with the =flycheck-compile= command.
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You can check what is wrong with flycheck with the =flycheck-compile= command.
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This will show you the exact command line used and its output.
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If you are using stack, check the [[Flycheck doesn't work with =stack=]] section.
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** Flycheck doesn't work with =stack=
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First check flycheck use the correct checker and all the path are properly configured using =flycheck-verify-setup= (~SPC e v~).
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You can force the checker by using =flycheck-select-checker= (~SPC e s~) to =haskell-stack-ghc=.
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If it still doesn't work, it could be one of the following problems :
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First check that flycheck uses the correct checker and all the paths are
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properly configured using =flycheck-verify-setup= (~SPC e v~). You can force the
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checker with =flycheck-select-checker= (~SPC e s~) to ensure it uses
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=haskell-stack-ghc=. If it still doesn't work, it could be one of the following
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problems:
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- stack build directory is wrong.
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- project root not set properly
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- The stack build directory is wrong
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- The project root is not set properly
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*** The stack build directory is wrong
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The path to the build directory containing some generated files is normally
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under =.stack-work/install/<os>/Cabal-<version>/build=.
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*** stack build directory is wrong
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The path to the build directory containing some generated files is normally under
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However, the version of the cabal library used by stack to generate the
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directory name is not the version of the cabal library installed by stack, but
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the version of cabal associated to the GHC version. This error can happen after
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upgrading cabal or cabal-install. To check if this is the problem, compare the
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path name of the build path used by flycheck using =flycheck-compile= and
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compare it to to the actual path in the =.stack-work= directory. If they are
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different you need to reinstall ghc using the command =stack setup
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--upgrade-cabal=.
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=.stack-work/install/<os>/Cabal-<version/build=.
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*** The Project root directory is not set properly
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Flycheck launches the GHC command not from the project root directory but from
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the the directory of the file being checked. This is normally not a problem as
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all the paths are set properly, however it could be a problem if some template
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Haskell functions use relative paths (e.g. in Yesod scaffolded projects).
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However, the version of the cabal library used by stack to generate the directory name is not
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the version of the cabal library installed by stack, but the version of cabal associated to the ghc version.
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This error can happen after upgrading cabal or cabal-install.
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To check if it's the problem, look at path name of the build pathn used by flycheck using =flycheck-compile= and compare it to
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to the actual name path in the =.stack-work= directory. If they mismatch you need to reinstall ghc using the command
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=stack setup --upgrade-cabal=.
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*** Project root directory not set properly
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Flycheck launch the ghc command not from the project root directory but from the the directory of the file being checked.
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This is not normally a problem as all the paths are set properly. However it could be a problem if some template haskell
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function uses relative paths (as found in Yesod scaffholded projects).
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Until it's fixed in flycheck the alternative is to the wrap the stack command to run all subcommand from the project root directory. You can do so with the following script:
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Until it's fixed in flycheck the workaround is to the wrap the stack command to
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run all subcommands from the project root directory. You can do so with the
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following script:
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#+BEGIN_SRC bash
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#!/bin/bash
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@ -511,16 +526,17 @@ cd `stack --project-root`
|
|||
stack $*
|
||||
#+END_SRC
|
||||
|
||||
and set the =flycheck-haskell-stack-ghc-executable= to it.
|
||||
Make sure you set =flycheck-haskell-stack-ghc-executable= to this script.
|
||||
|
||||
** haskell-mode commands don't work
|
||||
Some (most of) haskell-mode commands only works when haskell-mode is in interactive mode, .i.e as a interactive session associated to it.
|
||||
Load the buffer using ~SPC m s b~.
|
||||
** =ghc-mod= and =haskell-mode= commands overlaps. How do I know which command belongs to what ?
|
||||
ghc-mod commands are prefixed with =ghc-=, haskell-mode ones are prefixed with =haskell-=.
|
||||
** Some commands start with =ghc-= and some with =haskell-=. What does that mean ?
|
||||
Commands starting with =ghc-= are ghc-mod commands.
|
||||
Commands starting with =haskell-= are haskell-mode.
|
||||
|
||||
Some (most of) the haskell-mode commands only works when haskell-mode is in
|
||||
interactive mode, i.e. as a interactive session associated to it. Load it using
|
||||
~SPC m s b~.
|
||||
|
||||
** =ghc-mod= and =haskell-mode= commands overlap. How do I know which command belongs to what?
|
||||
ghc-mod commands are prefixed with =ghc-=, haskell-mode ones are prefixed with
|
||||
=haskell-=.
|
||||
|
||||
** Some commands start with =ghc-= and some with =haskell-=. What does that mean?
|
||||
Commands starting with =ghc-= are ghc-mod commands. Commands starting with
|
||||
=haskell-= are haskell-mode commands.
|
||||
|
|
|
|||
Loading…
Reference in New Issue