what does seq stand for in haskell

Question

I am new to haskell, and have just come to the lazy world proramming. I read that the seq function is very special because it forces to use a strict evaluation in order to be more efficient in some cases. But I just can't find what seq stand for literally. Maybe Strict Evaluation Q*???

Answer 1

seq evaluates its first argument before returning the second one. It is usually introduced to improve performance by avoiding unneeded laziness. It forces evaluation of the function.

seq :: a -> b -> b
seq _ y = y

from prelude.hs

This function definition is wrapped in #ifdef __HADDOCK__ so it will only be compiled by haddock (the documentation tool), not by the actual compiler! The 'real' seq is defined in GHC.Prim as

seq :: a -> b -> b; 
seq = let x = x in x. 

This is only a dummy definition. Basically seq is specially syntax handled particularly by the compiler. You wrote 'seq evaluates its first argument' - but first definition obviously does not do this.

via user2407038

More to read:

• On HaskellWiki
• Real World Haskell. Chapter 25. Profiling and optimization
• On StackOverflow
• Making Haskell programs faster and smaller
• How to avoid seq

Answer 2

It is supposed to remind you of "sequentially" or "sequence" because it allows the programmer to specify the sequence of evaluation of its arguments.