[Haskell-beginners] Concatenating lists

Jan Erik Moström lists at mostrom.pp.se
Thu Mar 22 15:44:21 CET 2012


Hi, 

I've just started to learn Haskell and played around a bit and tried this

1: let x = [1,2,3]
2: let x = x ++ [4,5,6]
3: x

The last line doesn't give a result. I assume that this is because 'x' is a name of a value, in the second line I redefine 'x' to a new value but Haskell doesn't evaluate the value until the last line but then 'x' becomes recursively defined in itself (the second x on line 2 is interpreted to refer to the value of the first x on line 2 and  not the value defined in line 1). This behavior is caused by the lazy evaluation in Haskell.

Have I understood this correctly?

- jem 





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