Real World Haskell - 第4章 Part7 How to think about loops (続き)

Real World Haskell で Haskell を継続的に勉強中。

Chapter 4. Functional programming
Chapter 4. Functional programming

How to think about loops

Left folds, laziness, and space leaks

• foldl は space leak を起こすので thunk を作らない foldl' を使うべし

ghci> foldl  (+) 0 [1..1000000]
*** Exception: stack overflow
ghci> :module +Data.List
ghci> foldl' (+) 0 [1..1000000]
500000500000