cabal - Installing Haskell dependencies like `pip -r requirements.pip` -

i new haskell , having problems cabal.

performing following operations,

$ cabal sandbox init $ cabal install parsec alex happy haddock mtl 

followed by

$ cabal configure --enable-tests resolving dependencies... configuring scheme-0.1.0.0... cabal: @ least following dependencies missing: alex >=2.3, cabal >=1.22, haddock >=2.15, happy >=1.18 

i using

$ cabal --version                         cabal-install version 1.22.8.0 using version 1.22.7.0 of cabal library  

i deleted sandbox , created new one

$ cabal sandbox remove $ cabal sandbox init 

so use:

$ cabal install --dependencies-only $ cabal configure --enable-tests 

but suffer same issue there, both yield same error, namely

resolving dependencies... configuring scheme-0.1.0.0... cabal: @ least following dependencies missing: alex >=2.3, cabal >=1.22, doctest >=0.8, haddock >=2.15, happy >=1.18 

this .cabal file,

name:                       scheme version:                    0.1.0.0 license:                    mit license-file:               license category:                   language build-type:                 simple cabal-version:              >=1.10  executable scheme   main-is:             main.hs   ghc-options:         -wall   hs-source-dirs:      src/   default-language:    haskell2010   build-depends:       base >=4.6 && <4.9                        , cabal >=1.22                        , parsec >=3.1 && <3.2                        , alex >=2.3                        , happy >=1.18                        , haddock >=2.15                        , mtl >=2.2.1  test-suite doctests   default-language:   haskell2010   type:               exitcode-stdio-1.0   ghc-options:        -threaded   main-is:            doctests.hs   build-depends:      base >=4.6 && <4.9                        , alex >=2.3                        , happy >=1.18                        , haddock >=2.13                        , doctest >= 0.8 

i experience same problems without sandbox.

in python pip matter of using virtualenv , executing pip install -r requirements.pip if 1 has such file specifying dependencies. i'd go through similar process, cabal.

what wrong approach?

so problem is

cabal: @ least following dependencies missing: alex >=2.3, cabal >=1.22, haddock >=2.15, happy >=1.18 

the missing deps here not libraries programs. have run cabal install on them, installs them special cabal bin folder, typically under unix in ~/.cabal/bin user installs. (and in different locations mac , windows).

so need ensure that bin directory in path, or need move executables /usr/bin or in path.