A type mismatch error is usually found in the context of strong typed languages. Occurs while assigning values between unrelated, incompatible or unconvertible values. For example assigning a string value to a number. The variable or property isn't of the correct type. For example, a variable that requires an integer value can't accept a string value unless the whole string can be recognized as an integer.
Questions tagged [type-mismatch]
730 questions
194
votes
4 answers
cannot convert data (type interface {}) to type string: need type assertion
I am pretty new to go and I was playing with this notify package.
At first I had code that looked like this:
func doit(w http.ResponseWriter, r *http.Request) {
notify.Post("my_event", "Hello World!")
fmt.Fprint(w, "+OK")
}
I wanted to…
Alfred
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82
votes
5 answers
Composing Option with List in for-comprehension gives type mismatch depending on order
Why does this construction cause a Type Mismatch error in Scala?
for (first <- Some(1); second <- List(1,2,3)) yield (first,second)
:6: error: type mismatch;
found : List[(Int, Int)]
required: Option[?]
for (first <- Some(1);…
Felipe Kamakura
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21
votes
1 answer
When does Haskell complain about incorrect typing in functions?
I am a Haskell newbie trying to wrap my head around type binding in functions and how Haskell enforces it. For example, even though the type for the fst function is fst :: (a, b) -> a, the compiler does not complain for the function fst'. But the…
user4132
- 317
- 1
- 6
21
votes
2 answers
Haskell scoping in nested function definitions using where
I have a problem with Haskell's scoping in where definitions. When I have the following function f, where I want to pass the x to the locally defined function f1 without explicitely using it as a parameter, I get an error saying that the type of x…
poke
- 307,619
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20
votes
1 answer
Option getOrElse type mismatch error
Why does this code raise a type mismatch error in Scala 2.9.2? I expected that getOrElse returns type String but actually it returns java.io.Serializable:
scala> implicit def StringToOption(s:String) = Option(s)
StringToOption: (s:…
sndyuk
- 2,513
- 2
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18
votes
1 answer
Covariance broken in C# arrays?
Consider following generic interface ITest with a covariant type parameter T, the generic class Test implementing the interface, and a class A and with a subclass B:
interface ITest
{
T prop{ get;}
}
class Test : ITest
{
…
JE42
- 4,152
- 4
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12
votes
4 answers
Classic ASP: I'm getting a type mismatch error when I shouldn't
I have a function for turning HTML encoded text back into HTML. It works great normally, but for some reason, I try to use it on some text today, and get the following error:
Microsoft VBScript runtime error '800a000d'
Type mismatch:…
James
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- 77
12
votes
5 answers
char and char* (pointer)
I would like to understand how pointers work, so i created this small program. first of all i create a p pointer, which points to a char.
The first question is at this point. If i create a pointer, the value of it is a memoryaddress (if i point it…
Iburidu
- 410
- 2
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- 15
11
votes
4 answers
Java: why do I receive the error message "Type mismatch: cannot convert int to byte"
If you declare variables of type byte or short and attempt to perform arithmetic operations on these, you receive the error "Type mismatch: cannot convert int to short" (or correspondingly "Type mismatch: cannot convert int to byte").
byte a =…
Brad Richards
- 1,123
- 3
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11
votes
2 answers
Type mismatch error in java 8
I have the following class with the following method.
public class MyClass {
public static T getSomeThing(final int id, final java.lang.reflect.Type type, final Map someThings) {
final String aThing =…
Naxos84
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- 1
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- 32
11
votes
3 answers
Create WCF client programmatically
I have a website with a Silverlight-enabled WCF service. The service works fine, and I can browse to the WSDL page in the browser with no problems.
Now, I am trying to create a client in a DLL. I need to create the whole client programmatically…
eidylon
- 6,621
- 18
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- 112
8
votes
2 answers
Inconsistent do notation in functions
Why is this function allowed:
-- function 1
myfunc :: String
myfunc = do
x <- (return True)
show x
and this is not:
-- function 2
myfunc :: String
myfunc = do
x <- getLine
show x
The compile error:
Couldn't match type `[]' with…
Gertjan Brouwer
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8
votes
1 answer
One or more parameter values were invalid: Type mismatch for key xyz expected: S actual: M
My AWS Lambda calls a DynamoDB based on this answer: https://stackoverflow.com/a/33649402/495455
import json
import boto3
client = boto3.resource('dynamodb')
table = client.Table("DS-Users")
def lambda_handler(event, context):
UserName =…
Jeremy Thompson
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8
votes
2 answers
Spring Mvc -- custom validation message for typeMismatch
I have a field that requires a double. If you enter a String, the default message is something like:
Failed to convert property value of type java.lang.String to required type java.lang.Double for property price; nested exception is…
user2892437
- 647
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- 21
8
votes
3 answers
What about John Hughes' `foldtree` am I misunderstanding?
John Hughes, in his famous article entitled Why Functional Programming Matters, describes data types for lists and ordered labelled trees,
listof * ::= Nil | Cons * (listof *)
treeof * ::= Node * (listof (treeof *))
and a function called…
jub0bs
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