/prog/ - Why not?

Name: Anonymous 2011-10-06 13:28



$ ghci

GHCi, version 6.8.2: http://www.haskell.org/ghc/  :? for help

Loading package base ... linking ... done.

Prelude> let yoba a b = if a < b then 123 else "abc"



<interactive>:1:29:

    No instance for (Num [Char])

      arising from the literal `123' at <interactive>:1:29-31

    Possible fix: add an instance declaration for (Num [Char])

    In the expression: if a < b then 123 else "abc"

    In the definition of `yoba':

        yoba a b = if a < b then 123 else "abc"

Prelude>

Name: Anonymous 2011-10-07 1:53

>>22
It doesn't work



$ ghci

GHCi, version 6.8.2: http://www.haskell.org/ghc/  :? for help

Loading package base ... linking ... done.

Prelude> let yoba a b = if a < b then Left 123 else Right "abc"

Prelude> (yoba 3 4)

Left 123

Prelude> (yoba 3 4)/2



<interactive>:1:0:

    No instance for (Fractional (Either t [Char]))

      arising from a use of `/' at <interactive>:1:0-11

    Possible fix:

      add an instance declaration for (Fractional (Either t [Char]))

    In the expression: (yoba 3 4) / 2

    In the definition of `it': it = (yoba 3 4) / 2

Prelude>

Why not?

1 Name: Anonymous 2011-10-06 13:28

24 Name: Anonymous 2011-10-07 1:53

Name: Anonymous 2011-10-06 13:28

Name: Anonymous 2011-10-07 1:53