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UnsupportedSubscript

rascal-0.40.17

Synopsis​

A subscript is applied to a value that does not support it.

Description​

Subscription is available for values of various types including: string, node, list, map, tuple and relation. This error is generated when subscription is applied to a value for which it is not defined.

Remedies:

  • Use another operation than subscription to extract the values you want.
  • Use another type (that does support subscription) to represent your data.

Examples​

Here are some correct uses of subscription:

rascal>"abc"[1];
str: "b"
---
b
---
rascal>[1,2,3][1];
int: 2
rascal>"f"(1,2,3)[1];
value: 2
rascal>("a":1, "b":2, "c":3)["b"]
int: 2

Here are some erroneous examples:

rascal>true[1];
|prompt:///|(5,1,<1,5>,<1,6>): subscript not supported on bool at |prompt:///|(5,1,<1,5>,<1,6>)
Advice: |https://www.rascal-mpl.org/docs/Rascal/Errors/CompileTimeErrors/UnsupportedOperation|
ok
rascal>123[1];
|prompt:///|(4,1,<1,4>,<1,5>): subscript not supported on int at |prompt:///|(4,1,<1,4>,<1,5>)
Advice: |https://www.rascal-mpl.org/docs/Rascal/Errors/CompileTimeErrors/UnsupportedOperation|
ok
rascal>{1,2,3}[1];
|prompt:///|(8,1,<1,8>,<1,9>): subscript not supported on set[int] at |prompt:///|(8,1,<1,8>,<1,9>)
Advice: |https://www.rascal-mpl.org/docs/Rascal/Errors/CompileTimeErrors/UnsupportedOperation|
ok