cabal list --installed cabal list gtools # searches Hackage If nothing appears, the package may be from a different ecosystem or a private repository. Cause: Your GHC version is too old or too new for the gtools version you’re trying to install. Fix: Use cabal install gtools --allow-older or switch GHC versions via ghcup . Error 3: "Cabal: Failed to build gtools: Missing foreign library" Some gtools versions depend on C libraries (e.g., gsl , blas ). Install them system-wide:
cabal install gtools-0.1.0.0 If you want to download and build gtools inside a project sandbox (to avoid dependency conflicts): gtools cabal download
Verify installation:
cabal --version # Output: cabal-install version 3.10.1.0 The typical cabal workflow involves updating your package list, then downloading and building gtools . Step 1: Update the Package Index cabal update This command downloads the latest list of packages from Hackage (Haskell’s central package repository). Step 2: Download Gtools Source (Without Installing) If you only want to download the source code without building it: cabal list --installed cabal list gtools # searches
cabal get gtools This fetches the tarball and extracts it into a directory named gtools-x.y.z . This is the closest to a literal operation. Step 3: Download and Build (Install Locally) To actually install the library so you can use it in your projects: Error 3: "Cabal: Failed to build gtools: Missing
If you’ve landed on this page searching for "gtools cabal download," you are likely a Haskell developer venturing into statistical computing, data visualization, or bioinformatics. Alternatively, you might be trying to replicate a research environment that depends on the gtools library—a powerful but often misunderstood package in the Haskell ecosystem.
cabal install gtools --lib The --lib flag ensures the library is registered globally for GHC.