Haskell has ghci, PureScript has psci -- an interactive REPL useful for
testing, exploring, and experimenting with code.
By default, psci doesn't load any libraries, so you can't do very much
without loading some libraries. You can load libraries manually from the REPL
using :l (and :f for the foreign files) or you can specify them via a glob
on startup (similar to how you use the compiler):
psci 'bower_components/purescript-*/src/**/*.purs' \
--ffi 'bower_components/purescript-*/src/**/*.js' \
'src/purs/**/*.purs' \
--ffi 'src/purs/**/*.js'
Note that pressing <TAB> will show you the available completions (often the
names in scope). I've found that to be particularly helpful. psci has a few
other useful commands that you can list with the :? command.
If you're working on a project, you can keep a .psci file that tells psci
which files to load on startup (:m for a PureScript module :f for a foreign
module):
cat .psci
:m src/purs/Main.purs
:m ../bower_components/purescript-console/src/Control/Monad/Eff/Console.purs
:m ../bower_components/purescript-eff/src/Control/Monad/Eff.purs
:m ../bower_components/purescript-eff/src/Control/Monad/Eff/Class.purs
:m ../bower_components/purescript-eff/src/Control/Monad/Eff/Unsafe.purs
:m ../bower_components/purescript-prelude/src/Prelude.purs
:f ../bower_components/purescript-console/src/Control/Monad/Eff/Console.js
:f ../bower_components/purescript-eff/src/Control/Monad/Eff.js
:f ../bower_components/purescript-eff/src/Control/Monad/Eff/Unsafe.js
:f ../bower_components/purescript-prelude/src/Prelude.js
When you've loaded a module, you can use its members fully qualified:
psci
> 1 Prelude.+ 1
2
To bring members into scope, use import:
> import Prelude
> 1 + 1
2
> import Main
> hello
Hello, psci!
unit
If you use a .psci file, you would usually set up your build system to
generate it to reflect your sources and the modules you have installed.
gulp-purescript and Pulp have support for this.