Smalltalk-style syntax

From Erights

User:Kevin Reid's idle speculation on an alternate surface syntax for E.

Translated mint example:

makeMint does {
  run: name = the any {
    [sealer, unsealer] = makeBrandPair run: name.
    mint does {
        __printOn: out = the void {
            out print: `<$name's mint>`.
        }
 
        makePurse: var balance an (int >= 0) = the any {
            decr does {
                run: amount an (0..balance) = the void {
                    set balance = balance - amount.
                }
            }.
            purse does {
                __printOn: out = the void {
                    out print: `<has $balance $name bucks>`.
                }
                getBalance = the int { balance }
                sprout     = the any { mint makePurse: 0 }
                getDecr    = the any { sealer seal: decr }

                deposit: amount an int  from: src = the void {
                    (unsealer unseal: src getDecr) run: amount.
                    set balance = balance + amount.
                }
            }.
            ^ purse
        }
    }.
    ^ mint
  }
}