[Haskell-beginners] Parse error

Brandon Allbery allbery.b at gmail.com
Wed Apr 15 16:26:14 UTC 2015


On Wed, Apr 15, 2015 at 12:21 PM, Shishir Srivastava <
shishir.srivastava at gmail.com> wrote:

> I am trying to run the following from the GHCi command prompt which
> results in parse error.
>

Urgh, sorry.

ghci is not ghc, and requires `let` even in the multi-line mode.

    :{
    let foo :: Maybe String
        foo = do
          x <- Just 3
          y <- Just "!"
          Just (show x ++ y)
    :}

In general, you are better off using files for definitions, and treat the
prompt as a debugger or desk calculator. Multi-line mode doesn't really
change this.

-- 
brandon s allbery kf8nh                               sine nomine associates
allbery.b at gmail.com                                  ballbery at sinenomine.net
unix, openafs, kerberos, infrastructure, xmonad        http://sinenomine.net
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20150415/bea06f95/attachment.html>


More information about the Beginners mailing list