Functional Patterns 🐱
Mewlix is imperative at heart, but it was written by someone addicted to functional programming. Because of this, functional programming patterns are supported in varying degrees.
Function Composition + Application
The function composition operator :> can be used to compose two functions:
mew h = f :> g -- Equivalent to: 🐈 (x) -> g(f(x))
The function application operator |> can be used for creating function pipes:
value |> f |> g |> h -- Equivalent to: h(g(f(x)))
Currying
Function currying can be done in Mewlix with a chain of anonymous function expressions.
This is affectionately nicknamed a kitty train:
🐈 (a) -> 🐈 (b) -> 🐈 (c) -> 🐈 (d) -> 🐈 (e) -> some_func(a, b, c, d, e)
Kitty trains can also be organized like this:
🐈 (a)
-> 🐈 (b)
-> 🐈 (c)
-> 🐈 (d)
-> 🐈 (e) -> some_func(a, b, c, d, e)
This can make them more readable when there are many parameters.
Curried Standard Library
Mewlix's standard yarn balls do not include curried functions. This is purely a design choice, as Mewlix is primarily an imperative language.
All standard yarn balls have curried variants one can import at any time, however.
A curried variant of a yarn ball includes all exports from the original yarn ball, and curries function with an argument count greater than 1. Constants and single-argument functions remain unchanged.
As such, the curried version can replace the original with no downsides.
std.curry
The curried variant of the std yarn ball:
takes std.curry as std_
[1, 2, 3] |> (do std_.map <- 🐈 (x) -> x * x) |> std_.meowf
-- prints: [1, 4, 9]
As the std yarn ball is always implicitly imported in every yarn ball, you can't import std.curry as std, as that will generate a name conflict.
To get around that, you should build your project with the --no-std compiler flag or add no-std to the 'flags' field in your project file.
After that, you're free to define your own std:
takes std.curry as std
std.console.curry
The curried variant of the std.console yarn ball, available in the console project mode:
takes std.console.curry as console
std.graphic.curry
The curried variant of the std.graphic yarn ball, available in the graphic project mode:
takes std.graphic.curry as graphic
Note: There may be a slight performance difference with curried functions in a game loop.