Error
Error prototype extensions
Import
_ <- fat.type.Error
Aliases
- AssignError: assigning a new value to an immutable entry
- AsyncError: asynchronous operation failure
- CallError: a call is made with insufficient arguments
- FileError: file operation failure
- IndexError: index is out of list/text bounds
- KeyError: the key (name) is not found in scope
- SyntaxError: syntax or code structure error
- TypeError: type mismatch on method call, return, or assign
- ValueError: type may be okay, but content is not accepted
Constructor
| Name |
Signature |
Brief |
| Error |
(val: Any) |
Return val coerced to text wrapped in error |
Prototype members
| Name |
Signature |
Brief |
| isEmpty |
<> Boolean |
Return true, always |
| nonEmpty |
<> Boolean |
Return false, always |
| size |
<> Number |
Return 0, always |
| toText |
<> Text |
Return error text val |
| freeze |
<> Void |
Make the value immutable |
Example
_ <- fat.type.Error
# Generating an error intentionally
x = Error('ops')
x.toText # yields "Error: ops"
# Inadvertently causing an error
e = undeclared.item # causes a TypeError
e.toText # yields "TypeError: can't resolve scope of 'item'"
Error aliases in practice
# Example of AssignError
x = 10
x = 20 # raises "AssignError: reassignment to immutable > x"
# Example of IndexError
list = [ 1, 2, 3 ]
list[5] # raises "IndexError: out of bounds"
# Example of CallError
add(10) # raises "CallError: nothing to call > add > ..."
See also