CODEWITHSUNDEEP
arraystypeslispcommon-lisp
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Reputation: 2165

simple-type-error

I've made an executable that includes calls to arrays. When I execute the program, I get the error

Condition of type: SIMPLE-TYPE-ERROR
In function AREF, the index into the object
 #(0.00387149 3.0345068e-4 5.9720734e-4 -1.6648759e-5 0.058811672).
takes a value 5 out of the range (INTEGER 0 4).

I looked up simple-type-error, and I believe it occurs when a value is of an unexpected type. However I was of the impression that you don't have to specify types in Lisp.

Upvotes: 0

Views: 692

Answers (1)

Rainer Joswig
Rainer Joswig

Reputation: 139311

You don't have to, but a Lisp system hopefully will complain when you call a function with the wrong type of object.

CL-USER 7 > (sin "a string")

Error: In SIN of ("a string") arguments should be of type NUMBER.

The LispWorks error report for your problem is bit less 'technical':

CL-USER 8 > (aref #(a b c d) 4)

Error: The subscript 4 exceeds the limit 3 for the first dimension 
of the array #(A B C D).

Which makes sense, since dimensions are zero-based. The above vector has index 0, 1, 2, and 3. But not 4.

CL-USER 10 > (typep 4 '(integer 0 3))
NIL

So 4 is not an integer in a range of 0 to 3.

Upvotes: 2

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