[Haskell-beginners] Parse error

[Brandon Allbery]

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
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