Haskell

5 readers

1 users here now

**The Haskell programming language community.** Daily news and info about all things Haskell related: practical stuff, theory, types, libraries, jobs, patches, releases, events and conferences and more... ### Links - Get Started with Haskell

founded 2 years ago

Laziness in Haskell — Part 3: Demand (www.youtube.com)

submitted 2 years ago by jaror@kbin.social to c/haskell@kbin.social

2 comments fedilink hide all child comments

To better understand some counterintuitive evaluation puzzles, we explore the notion of “demand” as it exists in Haskell and discuss how it influences GHC’s choice of evaluation strategy.

you are viewing a single comment's thread
view the rest of the comments

[–] jaror@kbin.social 2 points 2 years ago* (last edited 2 years ago)

I think pseq does have that "thunk forcing" behavior:

import GHC.Conc (pseq)

val :: Int
val = let x = error "x"
          y = error "y"
      in y `pseq` (x + y)

main = print val

I believe this is guaranteed to show the y error and not the x error.