Issa is in beta, expect bugs and API changes!
Features
-
Types from runtime checks
-
Pretty yet precise errors
-
Small, composable predicates
Installation
Wally
Add Issa to your wally.toml dependencies list:
[dependencies]
Is = "metatablesnow/issa@0.2.0"
Pesde
Add Issa to your pesde.toml dependencies list:
[dependencies]
Is = { name = "metatablesnow/issa", version = "0.2.0" }
Manual
Copy and paste the source code into a module script.
Guide
Every function in Is returns a Predicate.
local Is = require(path.to.Issa)
IsAge = Is.Number()
You can call a predicate:
local age = IsAge(18) -- This will pass, and return the input (18)
IsAge("Oops!") -- This will error
Try a predicate:
local success, data = IsAge:Try("Oops!")
-- success is false, and data is the error message
local success, data = IsAge:Try(18)
-- success is true, and data is the input (18)
Type a predicate:
type Age = typeof(IsAge.Type)
local bobsAge: Age = "Oops!" -- This will warn you!
use them to build more complex predicates:
local IsAnimal = Is.Interface({
Name = Is.String(),
Age = IsAge
})
or even refine them:
local IsAdult = Is.Refine(IsAnimal, function(self, animal)
-- Refinements run last, so no need to check if this is a table!
if animal.Age < 18 then
return Is.Fail(animal, "number over 18", "animals age is under 18", animal, "Age", "field")
end
return Is.Pass()
end)
IsAdult(13) -- This will error!