> It[Python] certainly does suggest there's compatibility with VAR syntax.

Maybe. Maybe not.

>It[Haskell, or do notation] also allows you to make declarations anywhere inside a block.

    main = do
        let x = 1
        let y = 2
        let z = 3
        let y = x
            z = y
            x = z
        print x

    => compilation error[1]

Do you find that normal?

How would you write what I wrote in Lisp in Haskell (for example using what you said)? Is it gonna need new concepts?

Compare:

    main = do
        let x = 1
        let y = 2
        let z = 3
        let y = x
        let z = y
        let x = z
        print [x, y, z]

    => [1, 1, 1] (as expected--but it's still dumb)

[1]

    a.hs:9:5: error:
        • Ambiguous type variable ‘a0’ arising from a use of ‘print’
          prevents the constraint ‘(Show a0)’ from being solved.
          Probable fix: use a type annotation to specify what ‘a0’ should be.
          These potential instances exist:
            instance Show Ordering -- Defined in ‘GHC.Show’
            instance Show a => Show (Maybe a) -- Defined in ‘GHC.Show’
            instance Show Integer -- Defined in ‘GHC.Show’
            instance Show () -- Defined in ‘GHC.Show’
            instance (Show a, Show b) => Show (a, b) -- Defined in ‘GHC.Show’
            instance (Show a, Show b, Show c) => Show (a, b, c)
              -- Defined in ‘GHC.Show’
            instance (Show a, Show b, Show c, Show d) => Show (a, b, c, d)
              -- Defined in ‘GHC.Show’
            instance (Show a, Show b, Show c, Show d, Show e) =>
                     Show (a, b, c, d, e)
              -- Defined in ‘GHC.Show’
            instance (Show a, Show b, Show c, Show d, Show e, Show f) =>
                     Show (a, b, c, d, e, f)
              -- Defined in ‘GHC.Show’
            instance (Show a, Show b, Show c, Show d, Show e, Show f,
                      Show g) =>
                     Show (a, b, c, d, e, f, g)
              -- Defined in ‘GHC.Show’
            instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g,
                      Show h) =>
                     Show (a, b, c, d, e, f, g, h)
              -- Defined in ‘GHC.Show’
            instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g,
                      Show h, Show i) =>
                     Show (a, b, c, d, e, f, g, h, i)
              -- Defined in ‘GHC.Show’
            instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g,
                      Show h, Show i, Show j) =>
                     Show (a, b, c, d, e, f, g, h, i, j)
              -- Defined in ‘GHC.Show’
            instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g,
                      Show h, Show i, Show j, Show k) =>
                     Show (a, b, c, d, e, f, g, h, i, j, k)
              -- Defined in ‘GHC.Show’
            instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g,
                      Show h, Show i, Show j, Show k, Show l) =>
                     Show (a, b, c, d, e, f, g, h, i, j, k, l)
              -- Defined in ‘GHC.Show’
            instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g,
                      Show h, Show i, Show j, Show k, Show l, Show m) =>
                     Show (a, b, c, d, e, f, g, h, i, j, k, l, m)
              -- Defined in ‘GHC.Show’
            instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g,
                      Show h, Show i, Show j, Show k, Show l, Show m, Show n) =>
                     Show (a, b, c, d, e, f, g, h, i, j, k, l, m, n)
              -- Defined in ‘GHC.Show’
            instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g,
                      Show h, Show i, Show j, Show k, Show l, Show m, Show n, Show o) =>
                     Show (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)
              -- Defined in ‘GHC.Show’
            instance Show a => Show (Solo a) -- Defined in ‘GHC.Show’
            instance Show Bool -- Defined in ‘GHC.Show’
            instance Show Char -- Defined in ‘GHC.Show’
            instance Show Double -- Defined in ‘GHC.Float’
            instance Show Float -- Defined in ‘GHC.Float’
            instance Show Int -- Defined in ‘GHC.Show’
            instance Show Word -- Defined in ‘GHC.Show’
            instance Show a => Show [a] -- Defined in ‘GHC.Show’
            ...plus 13 instances involving out-of-scope types
              instance Show GHC.Stack.Types.CallStack -- Defined in ‘GHC.Show’
              instance Show GHC.Types.KindRep -- Defined in ‘GHC.Show’
              instance Show GHC.Types.Levity -- Defined in ‘GHC.Show’
              instance Show GHC.Types.Module -- Defined in ‘GHC.Show’
              instance Show GHC.Num.Natural.Natural -- Defined in ‘GHC.Show’
              instance Show a => Show (GHC.Base.NonEmpty a)
                -- Defined in ‘GHC.Show’
              instance Show GHC.Types.RuntimeRep -- Defined in ‘GHC.Show’
              instance Show GHC.Stack.Types.SrcLoc -- Defined in ‘GHC.Show’
              instance Show GHC.Types.TrName -- Defined in ‘GHC.Show’
              instance Show GHC.Types.TyCon -- Defined in ‘GHC.Show’
              instance Show GHC.Types.TypeLitSort -- Defined in ‘GHC.Show’
              instance Show GHC.Types.VecCount -- Defined in ‘GHC.Show’
              instance Show GHC.Types.VecElem -- Defined in ‘GHC.Show’
        • In a stmt of a 'do' block: print x
          In the expression:
            do let x = 1
               let y = 2
               let z = 3
               let y = x
                   z = y
                   ....
               ....
          In an equation for ‘main’:
              main
                = do let x = ...
                     let y = ...
                     let z = ...
                     ....
      |
    9 |     print x
      |     ^^^^^

^ Are you sure you want this in your language? :)

> How would you write what I wrote in Lisp in Haskell

    main = do
        let x = 1
        let y = 2
        let z = 3
        let y' = x
            z' = y
            x' = z
        print [x', y', z']