[Haskell-beginners] Value from Monad

[Shishir Srivastava]

Hi,

Going through the '<-' description in 'learnouahaskell' it says -

*" If we have a Maybe String and we bind it with <- to a variable, that
variable will be a String"*

so if you write

do
str <- Just "3"

str should be of type 'String'. My question is how do I return "34"
by concatenating it to "4" because the following line of code fails -

---
do
str <- Just "3"
return str++"4"::Maybe String
---

or for that matter how can I return/print just the value of str from this
do block ?

Thanks,
Shishir
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