GHCi “let” — what does it do?

Question

I\'d appreciate if someone could point to docs on what "let" does in GHCi, or failing that, explain it convincingly.

So far as I can tell, "let" (

Answer 1

While programming in GHCi, you're like programming in the IO monad with do syntax, so for example you can directly execute an IO action, or use monadic bind syntax like r <- someIOFun.

let is also a part of do so you can also use this. I think it's being desugared into let .. in , so for example when you do this:

ghci> let a = 1
ghci> someFun
ghci> someFun2

It's like:

let a = 1 in
do someFun
   someFun2