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Haskell error when creating List comprehension
The 2019 Stack Overflow Developer Survey Results Are InBeginners Guide to Haskell?Getting started with HaskellWhat is Haskell actually useful for?What is “lifting” in Haskell?list comprehension vs. lambda + filterLarge-scale design in Haskell?Speed comparison with Project Euler: C vs Python vs Erlang vs HaskellHaskell: Lists, Arrays, Vectors, SequencesHaskell list comprehension errorUtilizing map in haskell on function arguments
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I'm following this guide to create a list comprehension.
data Value = Two|Three|Four|Five|Six|Seven|Eight|Nine|Ten|J|Q|K|A
deriving (Eq, Ord, Enum)
data Suite = Hearts | Spades | Diamonds | Clubs
deriving (Eq, Ord, Enum)
type Card = (Value, Suite)
pack :: [Card]
pack = [(Value,Suite) | Value <- [Two .. A], Suite <- [Hearts .. Clubs]]
When I create the pack function it always throws
error: Data constructor not in scope: Suite :: Suite
haskell functional-programming
edited Mar 22 at 21:49
Michael Litchard
1,99621542
asked Mar 22 at 4:33
Gusti AryaGusti Arya
765923
add a comment |
I'm following this guide to create a list comprehension.
data Value = Two|Three|Four|Five|Six|Seven|Eight|Nine|Ten|J|Q|K|A
deriving (Eq, Ord, Enum)
data Suite = Hearts | Spades | Diamonds | Clubs
deriving (Eq, Ord, Enum)
type Card = (Value, Suite)
pack :: [Card]
pack = [(Value,Suite) | Value <- [Two .. A], Suite <- [Hearts .. Clubs]]
When I create the pack function it always throws
error: Data constructor not in scope: Suite :: Suite
haskell functional-programming
edited Mar 22 at 21:49
Michael Litchard
1,99621542
asked Mar 22 at 4:33
Gusti AryaGusti Arya
765923
4
Variable names must begin with a lower case letter.
– Thomas M. DuBuisson
Mar 22 at 4:39
4
By the way, the word you're looking for is "suit". A suite is a set of rooms, a set of musical compositions, or probably since other things (none of them related to what you mean).
– dfeuer
Mar 22 at 4:46
add a comment |
I'm following this guide to create a list comprehension.
data Value = Two|Three|Four|Five|Six|Seven|Eight|Nine|Ten|J|Q|K|A
deriving (Eq, Ord, Enum)
data Suite = Hearts | Spades | Diamonds | Clubs
deriving (Eq, Ord, Enum)
type Card = (Value, Suite)
pack :: [Card]
pack = [(Value,Suite) | Value <- [Two .. A], Suite <- [Hearts .. Clubs]]
When I create the pack function it always throws
error: Data constructor not in scope: Suite :: Suite
haskell functional-programming
edited Mar 22 at 21:49
Michael Litchard
1,99621542
asked Mar 22 at 4:33
Gusti AryaGusti Arya
765923
I'm following this guide to create a list comprehension.
data Value = Two|Three|Four|Five|Six|Seven|Eight|Nine|Ten|J|Q|K|A
deriving (Eq, Ord, Enum)
data Suite = Hearts | Spades | Diamonds | Clubs
deriving (Eq, Ord, Enum)
type Card = (Value, Suite)
pack :: [Card]
pack = [(Value,Suite) | Value <- [Two .. A], Suite <- [Hearts .. Clubs]]
When I create the pack function it always throws
error: Data constructor not in scope: Suite :: Suite
haskell functional-programming
haskell functional-programming
edited Mar 22 at 21:49
Michael Litchard
1,99621542
asked Mar 22 at 4:33
Gusti AryaGusti Arya
765923
edited Mar 22 at 21:49
Michael Litchard
1,99621542
asked Mar 22 at 4:33
Gusti AryaGusti Arya
765923
edited Mar 22 at 21:49
Michael Litchard
1,99621542
edited Mar 22 at 21:49
Michael Litchard
1,99621542
edited Mar 22 at 21:49
Michael Litchard
1,99621542
1,99621542
asked Mar 22 at 4:33
Gusti AryaGusti Arya
765923
asked Mar 22 at 4:33
Gusti AryaGusti Arya
765923
asked Mar 22 at 4:33
Gusti AryaGusti Arya
765923
765923
4
Variable names must begin with a lower case letter.
– Thomas M. DuBuisson
Mar 22 at 4:39
4
By the way, the word you're looking for is "suit". A suite is a set of rooms, a set of musical compositions, or probably since other things (none of them related to what you mean).
– dfeuer
Mar 22 at 4:46
add a comment |
4
Variable names must begin with a lower case letter.
– Thomas M. DuBuisson
Mar 22 at 4:39
4
By the way, the word you're looking for is "suit". A suite is a set of rooms, a set of musical compositions, or probably since other things (none of them related to what you mean).
– dfeuer
Mar 22 at 4:46
4
4
Variable names must begin with a lower case letter.
– Thomas M. DuBuisson
Mar 22 at 4:39
Variable names must begin with a lower case letter.
– Thomas M. DuBuisson
Mar 22 at 4:39
4
4
By the way, the word you're looking for is "suit". A suite is a set of rooms, a set of musical compositions, or probably since other things (none of them related to what you mean).
– dfeuer
Mar 22 at 4:46
By the way, the word you're looking for is "suit". A suite is a set of rooms, a set of musical compositions, or probably since other things (none of them related to what you mean).
– dfeuer
Mar 22 at 4:46
add a comment |
1 Answer
1
active
oldest
votes
pack :: [Card]
pack = [(Value,Suite) | Value <- [Two .. A], Suite <- [Hearts .. Clubs]]
The left hand side of <- should be a variable (or a pattern w/ variables in it). In Haskell those start with a lowercase letter. Try this:
pack :: [Card]
pack = [(value,suite) | value <- [Two .. A], suite <- [Hearts .. Clubs]]
answered Mar 22 at 4:46
Colin BarrettColin Barrett
4,28612132
1
It's correct to say that the left-hand side of<-is a (refutable) pattern; a variable by itself is a valid pattern.
– chepner
Mar 22 at 11:27
You should look up the definition of the word "or" instead of trying to be pedantic. >:(
– Colin Barrett
Mar 24 at 16:36
add a comment |
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1 Answer
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active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
pack :: [Card]
pack = [(Value,Suite) | Value <- [Two .. A], Suite <- [Hearts .. Clubs]]
The left hand side of <- should be a variable (or a pattern w/ variables in it). In Haskell those start with a lowercase letter. Try this:
pack :: [Card]
pack = [(value,suite) | value <- [Two .. A], suite <- [Hearts .. Clubs]]
answered Mar 22 at 4:46
Colin BarrettColin Barrett
4,28612132
1
It's correct to say that the left-hand side of<-is a (refutable) pattern; a variable by itself is a valid pattern.
– chepner
Mar 22 at 11:27
You should look up the definition of the word "or" instead of trying to be pedantic. >:(
– Colin Barrett
Mar 24 at 16:36
add a comment |
pack :: [Card]
pack = [(Value,Suite) | Value <- [Two .. A], Suite <- [Hearts .. Clubs]]
The left hand side of <- should be a variable (or a pattern w/ variables in it). In Haskell those start with a lowercase letter. Try this:
pack :: [Card]
pack = [(value,suite) | value <- [Two .. A], suite <- [Hearts .. Clubs]]
answered Mar 22 at 4:46
Colin BarrettColin Barrett
4,28612132
1
It's correct to say that the left-hand side of<-is a (refutable) pattern; a variable by itself is a valid pattern.
– chepner
Mar 22 at 11:27
You should look up the definition of the word "or" instead of trying to be pedantic. >:(
– Colin Barrett
Mar 24 at 16:36
add a comment |
pack :: [Card]
pack = [(Value,Suite) | Value <- [Two .. A], Suite <- [Hearts .. Clubs]]
The left hand side of <- should be a variable (or a pattern w/ variables in it). In Haskell those start with a lowercase letter. Try this:
pack :: [Card]
pack = [(value,suite) | value <- [Two .. A], suite <- [Hearts .. Clubs]]
answered Mar 22 at 4:46
Colin BarrettColin Barrett
4,28612132
pack :: [Card]
pack = [(Value,Suite) | Value <- [Two .. A], Suite <- [Hearts .. Clubs]]
The left hand side of <- should be a variable (or a pattern w/ variables in it). In Haskell those start with a lowercase letter. Try this:
pack :: [Card]
pack = [(value,suite) | value <- [Two .. A], suite <- [Hearts .. Clubs]]
answered Mar 22 at 4:46
Colin BarrettColin Barrett
4,28612132
edited Mar 22 at 11:14
answered Mar 22 at 4:46
Colin BarrettColin Barrett
4,28612132
answered Mar 22 at 4:46
Colin BarrettColin Barrett
4,28612132
answered Mar 22 at 4:46
Colin BarrettColin Barrett
4,28612132
4,28612132
1
It's correct to say that the left-hand side of<-is a (refutable) pattern; a variable by itself is a valid pattern.
– chepner
Mar 22 at 11:27
You should look up the definition of the word "or" instead of trying to be pedantic. >:(
– Colin Barrett
Mar 24 at 16:36
add a comment |
1
It's correct to say that the left-hand side of<-is a (refutable) pattern; a variable by itself is a valid pattern.
– chepner
Mar 22 at 11:27
You should look up the definition of the word "or" instead of trying to be pedantic. >:(
– Colin Barrett
Mar 24 at 16:36
1
1
It's correct to say that the left-hand side of
<- is a (refutable) pattern; a variable by itself is a valid pattern.– chepner
Mar 22 at 11:27
It's correct to say that the left-hand side of
<- is a (refutable) pattern; a variable by itself is a valid pattern.– chepner
Mar 22 at 11:27
You should look up the definition of the word "or" instead of trying to be pedantic. >:(
– Colin Barrett
Mar 24 at 16:36
You should look up the definition of the word "or" instead of trying to be pedantic. >:(
– Colin Barrett
Mar 24 at 16:36
add a comment |
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4
Variable names must begin with a lower case letter.
– Thomas M. DuBuisson
Mar 22 at 4:39
4
By the way, the word you're looking for is "suit". A suite is a set of rooms, a set of musical compositions, or probably since other things (none of them related to what you mean).
– dfeuer
Mar 22 at 4:46