Small improvement discussion: Use `let` to lock variable previously declared as `var`

[dxb]

IMO the block syntax is good enough but I tried to come up with a template as 
an exercise. The code below works but can it be improved?

How to avoid passing the variable name (e.g. `foo`) to the template? As far as 
I know this isn't possible.
    
    
    template shadowvar(varname: untyped, initStmt: typed, body: untyped): 
untyped =
        block:
            var `varname` {.inject.} = initStmt
            body
            `varname`
    
    proc test() =
        let foo = shadowvar(foo, 5):
            foo += 2
        echo foo
    
    test()
    
    
    Run