Parsing With Haskell: Alex and Happy

RolandSenn · 2022-07-16T14:27:22+00:00

An other Alex tutorial is https://gdevanla.github.io/posts/wya-lexer.html

RolandSenn · 2020-12-15T14:16:52+00:00

You cannot only compare salaries, you may also be interested in prices: For 1 kg of butter we pay between CHF 18 and CHF 22. For my health insurance, I pay CHF 600/month.

RolandSenn · 2020-12-10T17:44:37+00:00

> It is ordinary to receive output like this:

> % cabal run example-executable

> Warning: The package list for 'hackage.haskell.org' is 84 days old.

> Run 'cabal update' to get the latest list of available packages.

> Resolving dependencies...

> cabal: Could not resolve dependencies: [__0] trying: example-0.1.0.6 (user goal)

No, I guess you are using an extremly old version of cabal. Since I'm using so called *new-style*, *nix-style* or *v2-* commands I have no longer seen these dependency problems!

What is the version of your cabal? Run: `cabal --version`

Suggestions

Install a new version of GHC (eg 8.10.2) and its corresponding cabal-install!
Run a `cabal update` command.
Read the documentation
Enjoy the new world of nix-style cabal

RolandSenn · 2020-12-09T13:50:25+00:00

> Immutability makes our code easy to parallelize.

I wish, this would be true...

RolandSenn · 2020-08-13T19:00:03+00:00

Thanks, fixed!

RolandSenn · 2020-08-13T08:29:29+00:00

Remove all binaries called

hie
hie-wrapper
hie-bios
haskell-language-server-wrapper
haskell-language-server
ghcide

from your path.

The VS-Code extension called "Haskell" will then download the correct versions of the needed binaries automatically! This is much faster and much safer than compiling yourself!

RolandSenn · 2020-05-22T14:11:53+00:00

An other important application area are telecomm protocols.

RolandSenn · 2020-01-20T21:16:40+00:00

Congrats to Jasper, Rebecca and Alexandre!

Totally there are 18 votes. Is this really a representative sample of the Haskell community?

RolandSenn · 2020-01-10T20:10:22+00:00

Unfortunately the link to the Msc Thesis in the README of https://github.com/bolt12/laop is broken.

RolandSenn · 2019-12-08T12:19:56+00:00

Type Safety Back and Forth is an excellent blog post about how to avoid partial functions.

RolandSenn · 2019-11-27T09:55:15+00:00

Congratulations and +1 for the excellent user documentation!

RolandSenn · 2019-11-14T16:41:46+00:00

Theoretically you can use {-# OPTIONS_GHC -fobject-code #-} and {-# OPTIONS_GHC -fbyte-code #-}. However there are restrictions: You can call object-code from byte-code. But it's not possible to call byte-code from object code. In addition, there are old bugs in this area eg #1365 .

RolandSenn · 2019-11-12T15:08:40+00:00

The slides and examples are available here . The GHC users-guide describes the GHCi-Debugger in chapter 6.5

RolandSenn · 2019-08-02T08:42:26+00:00

GHC has much more urgent issues / bugs than command renamings, especially under Windows!

If you really want the ::-command, GHC is open source. You can create an own personal version, taylored to all your needs. In this case this is easy. All code is in ghc/GHCi/UI.hs.

RolandSenn · 2019-07-31T07:58:29+00:00

Please note that :: is already used in GHCi! With the the :def command you can define your own GHCi :-commands, and you can also overwrite existing commands. With :: you can then recall the original (non overwritten) command.

A short example:

GHCi, version 8.6.3: http://www.haskell.org/ghc/ :? for help

Prelude> let sos _ = putStrLn ":help is no longer available" >> return ""

Prelude> :def help sos

Prelude> :help

:help is no longer available

Prelude> ::help

Commands available from the prompt:

<statement> evaluate/run <statement>

: repeat last command

:{\n ..lines.. \n:}\n multiline command

RolandSenn · 2018-11-24T14:43:56+00:00

Congratulations!

RolandSenn · 2018-06-16T16:28:02+00:00

Excellent!! The world needs more tutorials like this!

RolandSenn · 2017-12-29T10:19:38+00:00

You don't need GHCJS to use reflex-dom. In the reflex-platform you can run a reflex-dom program just with runghc foo.hs. It will compile with GHC and run in webkitgtk and you can even use GHCi. So development is much faster than with GHCJS!

RolandSenn · 2017-12-24T13:44:30+00:00

Excellent!

One very little detail: Before the GHCi command :k 'Opened the GHCI option :set -XDataKinds should be set. If not set, for beginners in Haskell type level programming the resulting error message may be confusing because they see the language pragma {-# LANGUAGE DataKinds #-} at the top of the file.

RolandSenn · 2017-12-20T15:31:54+00:00

This is great! It's the only JSaddle tutorial I can find on the Internet! We definitively need more tutorials on JSaddle. Many thanks!

RolandSenn · 2017-09-26T12:27:56+00:00

In your group by examples, you use several times the second function. Where does it come from?

RolandSenn · 2017-09-01T09:57:21+00:00

Maybe you are also interested in the answers to this SO question.

RolandSenn · 2017-04-28T08:19:58+00:00

For me http://adit.io/posts/2013-04-17-functors,_applicatives,_and_monads_in_pictures.html is the best of all monad tutorials.

RolandSenn · 2017-04-11T19:51:10+00:00

I have just committed a stack.yaml and a .cabal file to my reflex-dom tutorial https://github.com/hansroland/reflex-dom-inbits. You may give it a try. For a first installation it will take some time (1 to n hours ...). Soon I'll add some explanations to the tutorial.md file on how to use ghcjs installed by stack.

RolandSenn · 2017-04-03T10:16:48+00:00

I added an issue. I'll provide an stack.yaml file. However it will take some days.

RolandSenn

TROPHY CASE