parsec VS ghc

Writing Haskell programs that rely on third-party packages is still an issue when it’s a not actively maintained package. They get out of date with the base library (Haskell’s standard library), and you might see yourself in a situation where you need to downgrade to an older version. This is not exclusive to Haskell, but it happens more often than I’d like to assume. However, if you only rely on known well-maintained libraries/frameworks such as Aeson, Squeleto, Yesod, and Parsec, to name a few, it’s unlikely you will face troubles at all, you just need to be more mindful of what you add as a dependency. There’s stackage.org now, a repository that works with Stack, providing a set of packages that are proven to work well together and help us to have reproducible builds in a more manageable way—not the solution for all the cases but it’s good to have it as an option.

The Parsec library for Haskell uses combinators, and there are a few good resources around the internet which explore it, if you know Haskell.

Parse the expression using parsec library ( if you're unfamiliar with it please check out https://hackage.haskell.org/package/parsec) it's a strong library for parer combinators. Once you parse the expression u need to define and sum up the similar terms. Check this example out - https://fpunfold.com/2020/05/18/making-a-calculator-in-haskell-with-parsec.html

Konbini is a functional parser combinator library inspired by Haskell parsing libraries like Parsec. It's (hopefully) fairly easy to use, and is about as performant as the better-parse library. In fact, it's quite similar to better-parse in many aspects. The main difference is in how parsers are composed. Where better-parse prefers operators and infix functions, Konbini instead uses plain functions.

Hi everyone, I'm learning F# and currently trying to do a Parsec-like CE, just to get comfortable with computation expressions.

good libraries for parsing: parsec, attoparsec etc.

Thank you! When I read the title I only knew about https://hackage.haskell.org/package/parsec, and for a moment I was very confused…

The more "idiomatic" way would be to use a parser library, e.g. parsec, attoparsec, or megaparsec. But even then I think it would be a lot easier to maintain if you could preserve the angle brackets <> in the input.

of course it does! what else would you call something like chicken scheme [https://call-cc.org/], ats [https://ats-lang.sourceforge.net/], or ghc [https://www.haskell.org/ghc/]? they are not "scripts", they are full-blown compilers that happen to use C as their compilation target, and then leverage C compilers to generate code for a variety of architecures. it's a very sensible way to do things.

Agree about Haskell... as far as I'm aware there is actually no declarative/easily-readable definition of the Haskell syntax that is also complete, especially when it comes to the indentation rules, and the syntax is basically defined by the very (ironically) imperatively-defined GHC parser[0].

I prefer a syntax like in Pure[1], where the ambiguous, hard to parse indentation-based syntax is replaced by explicit semicolons (Yeah, you can use braces/semicolons in Haskell as well, but most code doesn't).

[0] https://github.com/ghc/ghc/blob/master/compiler/GHC/Parser/L...

[1] https://agraef.github.io/pure-lang/

GHC, the main Haskell compiler

GHCi, version 9.6.3: https://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /Users/daniel/.ghci ghci> :{ | split :: Float -> [Int] | split value = map(read . (:[])) . show | :} :3:15: error: [GHC-83865] • Couldn't match expected type: [Int] with actual type: a0 -> [b0] • Probable cause: ‘(.)’ is applied to too few arguments In the expression: map (read . (: [])) . show In an equation for ‘split’: split value = map (read . (: [])) . show

GHC is hosted on Gitlab, the Github repo is just a mirror. So money.

https://github.com/ghc/ghc

☁ ~ ghci GHCi, version 9.4.7: https://www.haskell.org/ghc/ :? for help ghci> 6 + 3^2 * 4 42

Depending on who you ask, a programming language can be different things. If you ask the Haskell community, many will tell you that the language is the Haskell specification, and that what currently is being used is not Haskell itself, but an extension of Haskell that is supported by the GHC compiler. Similar to the C language, a programming language would be a specification.

GHCi, version 9.4.2: https://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from ~/.dotfiles/ghc/.ghc/ghci.conf