diff --git a/Cabal/doc/installing-packages.markdown b/Cabal/doc/installing-packages.markdown index ca881e51e2e309c69ebb606a3269c78dd074142e..48c1e60d5ccaf06120019e8b19eb4c94a8b88dd9 100644 --- a/Cabal/doc/installing-packages.markdown +++ b/Cabal/doc/installing-packages.markdown @@ -755,6 +755,16 @@ be controlled with the following command line options. It's also possible to enable `--allow-newer` permanently by setting `allow-newer: True` in the `~/.cabal/config` file. +`--constraint=`_constraint_ +: Restrict solutions involving a package to a given version range. + For example, `cabal install --constraint="bar==2.1"` will only consider + install plans that do not use `bar` at all, or `bar` of version 2.1. + + As a special case, `cabal install --constraint="bar -none"` prevents + `bar` from being used at all. (`-none` abbreviates `> 1 && < 1`) + `cabal install --constraint="bar installed"` prevents reinstallation + of the `bar` package. + ## setup build ## Perform any preprocessing or compilation needed to make this package ready for installation.