Is there a way to capture a value from the left expression and use it on the right expression?

Question

I want to modify or compute a value before assigning it to a const. Is there a way to do this in a single line expression?

I can use labeled block syntax, but I’m wondering if there’s another syntax that would be easier to read.

const std = @import("std");

const print = std.debug.print;

fn f(x: i32) i32 {
    return x + 1;
}

pub fn main() void {
    {
        const x, const y = blk: {
            const a = f(2);

            break :blk .{ a * a, a + a };
        };
        print("{d}, {d}\n", .{ x, y });
    }

    {
        // Is there a way to do something like this
        // const x, const y = f(2) |a| .{ a * a, a + a };
        // print("{d}, {d}\n", .{ x, y });

        // Not like this
        const x, const y = if (@as(?i32, f(2))) |a| .{ a * a, a + a } else unreachable;
        print("{d}, {d}\n", .{ x, y });
    }

    {
        // Is there a way to do something like this
        // f(2) |a| .{ a * a, a + a } |x,y| print("{d}, {d}\n", .{ x, y });

        // Not like this
        if (@as(?struct { i32, i32 }, if (@as(?i32, f(2))) |a| .{ a * a, a + a } else unreachable)) |a| print("{d}, {d}", .{ a.@"0", a.@"1" }) else unreachable;
    }
}

sigod · Accepted Answer · 2025-11-28 03:23:44Z

0

No, there is not. Zig is not a functional programming language.

Do this instead:

const a = f(2);
const x = a * a;
const y = a + a;
print("{d}, {d}\n", .{ x, y });

Or this:

const a = f(2);
print("{d}, {d}\n", .{ a * a, a + a });

answered yesterday

sigod

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