How to change a variable's value in GHCI debugger?

Question

Is it possible to change a variable's value in GHCI debugger? If yes, please show me how?

No, one of the important design principles of Haskell is that *all* variables are immutable. — Willem Van Onsem, Aug 02 '18 at 16:48
Possible duplicate of [In ghci, how to remove an existing binding?](https://stackoverflow.com/questions/44894152/in-ghci-how-to-remove-an-existing-binding) — Gurkenglas, Aug 02 '18 at 19:57

score 0 · Answer 1 · answered Aug 07 '18 at 18:53

If you have a variable first defined as:

x = 7 :: Integer

Then if you want to redefine x, then all you need to do is:

x = "Hello!"

Note that this will not affect functions whose body contains x, for example:

> x = 7 : Integer
> f = (+ x)
> f 10
17
> x = "Hello!"
> f 10
17

You will have to redefine any function whose body contains x in order for the change to take affect.

1 Answers1