purescript Questions

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At this point in my learning journey, I simply accepted that this function is called pure (both in Haskell and in PureScript), but it would have helped a lot if I had known the reasoning behind thi...
Photocomposition asked 1/6, 2024 at 12:6

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In real world application I noticed a pattern that could be generalized to something like: purescript: class Profunctor p <= Zero p where pzero :: forall a b. p a b -- such that `forall f g. di...

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Issue Following is a minimal, contrived example: read :: FilePath -> Aff String read f = do log ("File: " <> f) -- (1) readTextFile UTF8 f -- (2) I would like to do some debug...

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I'm using purescript-halogen to build a spreadsheet-like table (similar to Handsontable). If you double-click a cell, an html input element is rendered as a child of the respective table cell (and ...
Shawndashawnee asked 27/8, 2015 at 12:7

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I saw this question: Force show a record in PureScript where I found out I can use purescript-debug to print it, e.g. by using: > traceAny {a:1} id { a: 1 } unit I was wondering however w...
Blowpipe asked 16/2, 2017 at 19:30

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I'm reading PureScript by Example and got to the part introducing the Reader monad. The example goes like this: createUser :: Reader Permissions (Maybe User) createUser = do permissions <- ask...
Drugstore asked 13/10, 2017 at 21:20

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I'm looking for an idiomatic way to write a function List Char -> String in Purescript. This seems like a simple thing to do, but I'm new to Purescript and have been browsing documentation for ...
Primordium asked 2/1, 2016 at 10:49

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Problem: I have different record types with many common fields. How could I "include" the common fields in the record type definitions? Example: newtype RecordType1 = RecordType1 { a :: Int, b ::...
Roadhouse asked 23/8, 2018 at 13:25

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I am very new to Purescript so this might be a naive question. I want to write a Purescript function that reads input from HTML input elements on the browser and writes some output to another HTM...
Abundant asked 25/5, 2020 at 11:29

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everyone! I'm a Purescript beginner and have trouble with working on records. I have one record type: type Employee = { firstName :: String , lastName :: String , address :: String , height ...
Kimberykimble asked 30/12, 2019 at 14:45

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I've been trying to develop a component system in Purescript, using a Component typeclass which specifies an eval function. The eval function for can be recursively called by a component for each s...
Paulie asked 19/7, 2018 at 12:14

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I am attempting to learn purescript. I have a button in some HTML that I am trying to print the class name of. I am building and browserifying using pulp. The function I am using is querySelect...
Sisco asked 10/8, 2018 at 7:22

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While testing, I’d like to read and write a file from and to disk (JSON in, JSON out). How do I do this in PureScript? In Haskell I have something like main :: IO () main = do input <- readFil...
Yentai asked 29/2, 2016 at 16:58

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In their paper on profunctor optics, Pickering et al. state that The term ‘profunctor’ comes from category theory, although much of the categorical structure gets lost in translation. That see...

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There are several UI libraries for the PureScript, such as purescript-thermite, purescript-halogen, purescript-react-simple and other. Which library is right for the production?
Pickard asked 13/3, 2018 at 6:7

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Assume I have User records in my PureScript code with the following type: { id :: Number , username :: String , email :: Maybe String , isActive :: Boolean } A CommonJS module is derived from th...
Tarim asked 11/1, 2015 at 8:24

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In Haskell I can write a multi-line statement on a single line, like do {x<-[1,2];y<-[3,4];return (x,y)} but in Purescript even a single-statement do-statement with curly braces will not c...
Cerated asked 28/9, 2017 at 4:57

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Tried to use (.) for function composition, but it doesn't work. import Data.String (length, trim) trimmedLength :: String -> Int trimmedLength = length . trim
Courthouse asked 16/9, 2017 at 11:2

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I am trying to setup hello world project with purescript on NixOs and have couple questions, Official purescript website recommend installation via npm but there is no nixos.nodePackages.purescri...
Illnatured asked 7/9, 2017 at 10:38

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What does the period / dot mean? forall a. Num a => a -> a -> a Is it merely a separator?
Jason asked 9/9, 2017 at 23:30

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In PureScript, how does List differ from Array? What are the reasons to use one over the other?
Melgar asked 27/6, 2017 at 21:15

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PureScript looks very similar to Haskell. It seems to me that large parts, mostly the pure parts, of a PureScript program should be compilable as well by a Haskell compiler. Is that right? This le...
Albemarle asked 30/10, 2014 at 20:47

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I am trying to build my react-native project and using react-native-fbsdk. I am using [email protected] and, [email protected]. When I build my project I got this error on execution scr...

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Given I have the folowing records in purescript: let name = {name: "Jim"} let age = {age: 37} is it possible to combine those two records some how in a generic way? Something like: name 'comb' ...
Motorboating asked 14/3, 2016 at 10:59

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This seems to me a weird question, but I have gone through the purescript-datetime and purescript-js-date and I just cannot find a way to get current DateTime. Is there some hidden library function...
Behindhand asked 10/4, 2017 at 14:0

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