lsmor

Set Up a Haskell Development Environment in Three Steps

a Haskell Development Environment consist in a compiler (ghc), a language server (hls), a building tool (cabal or stack), and an editor compatible with the language server protocol.

The best way to have a coherent installation of these components is with the ghcup tool.

• Step 1: Install GHCup. You'll be prompted to install some tools. Say yes to hls. Do not install stack yet (see below).
• Step 2: Install vscode
• Step 3: Open vscode and install the haskell extension either using the extension panel or pressing CTRL+P and ext install haskell.haskell.

gelisam

-- An alternative representation of optics.
--
-- I represent an optic as the set of actions it supports. Composition
-- intersects the sets, which is how e.g. composing a Lens with a Prism gives a
-- Traversal.

{-# LANGUAGE DataKinds, FlexibleContexts, FlexibleInstances, GADTs, KindSignatures, MultiParamTypeClasses, RankNTypes, TypeFamilies, TypeOperators, UndecidableInstances #-}
{-# OPTIONS -Wno-name-shadowing #-}
module Main where
import Test.DocTest

dtaskoff

install stack

CentOS-specific preparations:

yum install ncurses-devel gcc-c++
localedef -c -f UTF-8 -i en_US en_US.UTF-8
export LC_ALL=en_US.UTF-8

Building the binary distribution: