tschemel

proc unknown {cmd args} {
    upvar 1 $cmd cmdvar
    if {[info exists cmdvar]} {
        uplevel 1 [list $cmdvar {*}$args]
    } else {
        apply $cmd {*}$args
    }
}

# now we can dispense with [proc]!
set lambda {{args body} {list $args $body}}
set proc {{name args body} {uplevel 1 [list set $name [list $args $body]]}}

# scheme's (define) for Tcl
set define {{name value} {
  if {[llength $name] > 1} {
    set args [lassign $name name]
    set value [list $args $body]
  }
  set $name $value
}

define {square a} {* a a}

# an accumulator
proc accumulator {initial} {
  lambda {addend} {
    incr initial $addend
  }
}

# is there room to attach bytecode to a variable that contains a lambda?

# we still lack proper closures. [sproc] seems to have an approach for that.

# hygienic macros are completely another story