Welcome to the GHC User’s Guide¶. Contents: 1. Introduction. Obtaining GHC; Meta-information: Web sites, mailing lists, etc. GHCi commands The:set and:seti commands GHCi options Setting GHC command-line options in GHCi Setting options for interactive evaluation only www.doorway.ru file Compiling to object code inside GHCi FAQ and Things To Watch Out For 3. Using runghc Flags 4. Using GHC Getting started. · Type inference in GHCi vs. manual signature. Ask Question Asked 9 years, 10 months ago. Active 9 years, 10 months ago. Viewed 3k times 4 2. when I type:t map length. sum into GHCi, it says that the type would be: Haskell tells you that your expression had a valid type, namely [[[a]]] -.
Haskell tells you that your expression had a valid type, namely [[[a]]] - [Int] if only [[a]] would be an instance of Num. This is like some girls telling you she will go out with you when hell freezes over. Steps to setup ghc and cabal are given in the ghc ppa. Packages from the PPA can be installed as follows: sudo add-apt-repository -y ppa:hvr/ghc sudo apt-get update sudo apt-get install -y cabal-install-XXX ghc-YYY. Packages are installed into /opt/ghc/bin and /opt/cabal/bin. We'll explain most of these commands as we go along, and there is complete documentation for all the commands in Section , “GHCi commands”. Haskell expressions can be typed at the prompt: Prelude 1+2 3 Prelude let x = 42 in x / 9 Prelude GHCi interprets the whole line as an expression to evaluate.
The Glorious Glasgow Haskell Compilation System User's Guide, Version The GHC Team. Table of Contents. The Glasgow Haskell Compiler License · 1. GHC now allows users to manually define the specificity of type variable binders. By marking a variable with braces {tyvar} or {tyvar:: kind}, it becomes. GHC has a number of options that select which types of non-fatal error This option is not on by default, having to be turned on manually or with.
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