davidallsopp/multiline.hs

Created June 20, 2015 20:11

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Multi-line entry in GHCI

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multiline.hs

	import Control.Monad.State

	:{
	let test :: State Int Int
	test = do
	put 3
	modify (+1)
	get
	:}

	print $ execState test 0

Author

davidallsopp commented Jun 22, 2015

Another do-block example, with equivalent >>=

Prelude> [1,2,3] >>= \x -> [x,x] >>= \x -> [x+1]
[2,2,3,3,4,4]

Prelude> :{
Prelude| do
Prelude|   x <- [1,2,3]
Prelude|   [x,x]
Prelude| :}

[1,1,2,2,3,3]

Prelude> :{
Prelude| do
Prelude|   x <- [1,2,3]
Prelude|   y <- [x,x]
Prelude|   [y+1] -- or return (y+1)
Prelude| :}

[2,2,3,3,4,4]

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