Isaac Dupree wrote:
David Carter wrote:
This is all as I would expect so far, but:
Prelude> let sqlist = map sq
Prelude> :t sqlist
sqlist :: [Integer] -> [Integer]
And indeed, I get
Prelude> sqlist [2.5]
<interactive>:1:8:
No instance for (Fractional Integer)
... etc
The dreaded Monomorphism Restriction, which GHCi chooses to apply
after every line you input. You could say "let sqlist a = map sq a"
(syntactically having arguments makes the defaulting of (Num a => [a]
-> [a]) not apply), or just use `ghci -fno-monomorphism-restriction`.
Isaac
Thanks -- I had a feeling I'd seen something about it before, but
couldn't remember where.
Anyway it's good to know the syndrome has a name and a prevention
strategy, even if not a cure :-).
David
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