ghci-7.0.4: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/ghci-7.0.4 - from package: ghc-compiler

You may install the required package with command yum install {package}
Error in other languages:
ghci-7.0.4: bevel nie gevind nie
ghci-7.0.4: comandă negăsită
ghci-7.0.4: comando não encontrado
ghci-7.0.4: commande introuvable
ghci-7.0.4: command not found
ghci-7.0.4: käsku ei ole
ghci-7.0.4: không tìm thấy lệnh
ghci-7.0.4: komanda nerasta
ghci-7.0.4: Kommando nicht gefunden.
ghci-7.0.4: kommandot finns inte
ghci-7.0.4: komut yok
ghci-7.0.4: nie znaleziono polecenia
ghci-7.0.4: níor aimsíodh an t-ordú
ghci-7.0.4: no se encontró la orden
ghci-7.0.4: no s'ha trobat l'ordre
ghci-7.0.4: opdracht niet gevonden
ghci-7.0.4: parancs nem található
ghci-7.0.4: perintah tidak ditemukan
ghci-7.0.4: príkaz nenájdený
ghci-7.0.4: příkaz nenalezen
ghci-7.0.4: команда не найдена
ghci-7.0.4: командата не е открита
ghci-7.0.4: 命令找不到
ghci-7.0.4: コマンドが見つかりません