
juhp
Effective Haskell: "one" :: Int error message (p99)
In ch3, section on Reading Type Errors, the error message presented for "one " :: Int
with IsString
seems non-standard, ie not from a minimal ghci session perhaps? Also note the space after e.
For all current GHC 9 versions I get;
ghci> "one" :: Int
<interactive>:1:1: error:
• Couldn't match type ‘[Char]’ with ‘Int’
Expected: Int
Actual: String
• In the expression: "one" :: Int
In an equation for ‘it’: it = "one" :: Int
(ghc-8.10 is slightly different but also no IsString.)
Of course it’s quite likely one will run into the IsString error IRL…
Most Liked

RebeccaSkinner
Author of Effective Haskell
Oh yeah, that’s a great catch. I had a few default extensions enabled in ghci, including OverloadedStrings
. I’ll get some errata up soon with the set of default extensions and some additional explanation. Thanks!
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