Introduction
Result type that can hold either a value or an error, but not both
Usage
Add the following to your .nimble file:
requires "result"
or just drop the file in your project!
Example
import result
# It's convenient to create an alias - most likely, you'll do just fine
# with strings as error!
type R = Result[int, string]
# Once you have a type, use `ok` and `err`:
proc works(): R =
# ok says it went... ok!
R.ok 42
proc fails(): R =
# or type it like this, to not repeat the type!
result.err "bad luck"
if (let w = works(); w.isOk):
echo w[], " or use get(): ", w.get()
# In case you think your callers want to differentiate between errors:
type
Error = enum
a, b, c
type RE[T] = Result[T, Error]
# In the expriments corner, you'll find the following syntax for passing
# errors up the stack:
proc f(): R =
let x = ?works() - ?fails()
assert false, "will never reach"See result.nim for more in-depth documentation - specially towards the end where there are plenty of examples!
License
MIT license, just like Nim, or Apache, if you prefer that