Concepts

The Concepts library provides compile-time validation of type constraints.

Contents

• Overview
• Installation
• API Reference
• License

Overview

A trait is a property of a type (e.g., isIntegral). A concept is a named set of traits (e.g., integral).

const std = @import("std");

const concepts = @import("concepts");

pub fn main() anyerror!void {
    comptime {
        concepts.integral(i32);
        concepts.same(i32, i32);

        arrayList(std.ArrayList(u8));
        arrayList(std.ArrayListUnmanaged(u8)); // error: concept `ArrayList` was not satisfied
    }
}

/// arrayList is a concept that requires `T` to be a `std.ArrayList`.
fn arrayList(comptime T: type) void {
    comptime concepts.Concept("ArrayList", "")(.{
        concepts.traits.hasDecl(T, "Slice"),
        concepts.traits.isSlice(T.Slice),
        concepts.traits.isSame(T, std.ArrayList(std.meta.Child(T.Slice))),
    });
}

Installation

Manual

1. Install the library.

   git clone https://github.com/ibokuri/concepts lib/concepts
   

2. Add the library as a package in build.zig.

   const std = @import("std");
   
   pub fn build(b: *std.build.Builder) void {
   
       ...
   
       obj.setTarget(target);
       obj.setBuildMode(mode);
   +   obj.addPackagePath("concepts", "lib/concepts/src/lib.zig");
       obj.install();
   }

Gyro

1. Install the library.

   gyro add -s github ibokuri/concepts
   gyro fetch
   gyro update
   

2. Add the library as a package in build.zig.

   const std = @import("std");
   +const pkgs = @import("deps.zig").pkgs;
   
   pub fn build(b: *std.build.Builder) void {
   
       ...
   
       obj.setTarget(target);
       obj.setBuildMode(mode);
   +   pkgs.addAllTo(obj);
       obj.install();
   }

API Reference

concepts

General

• err - Generates a compile error due to an invariant violation during concept validation.
• fail - Generates a compile error due to a concept being unsatisfied.

Concepts

• container - Specifies that a type is a container type.
• decl - Specifies that a type contains a given declaration.
• extern - Specifies that a type has an extern in-memory layout.
• field - Specifies that a type contains a given field.
• float - Specifies that a type is a floating-point type.
• integral - Specifies that a type is an integral type.
• method - Specifies that a type contains a given function.
• packed - Specifies that a type has a packed in-memory layout.
• same - Specifies that a type is the same as another type.
• signedIntegral - Specifies that a type is an integral type that is signed.
• slice - Specifies that a type is a slice type.
• string - Specifies that a type is a string type.
• tuple - Specifies that a type is a tuple type.
• unsignedIntegral - Specifies that a type is an integral type that is unsigned.

concepts.traits

Traits

• hasDecl - Checks if a type contains a given declaration.
• hasDecls - Checks if a type contains a given set of declarations.
• hasField - Checks if a type contains a given field.
• hasFields - Checks if a type contains a given set of fields.
• hasFunction - Checks if a type contains a given function.
• hasFunctions - Checks if a type contains a given set of functions.
• isContainer - Checks if a type is a container type.
• isExtern - Checks if a type has an extern in-memory layout.
• isFloat - Checks if a type is a floating-point type.
• isIntegral - Checks if a type is an integral type.
• isPacked - Checks if a type has a packed in-memory layout.
• isSame - Checks if two types are equal.
• isSignedIntegral - Checks if a type is an integral type that is signed.
• isSlice - Checks if a type is a slice type.
• isString - Checks if a type is a string type.
• isTuple - Checks if a type is a tuple type.

License

See LICENSE for more detail.