Runtime evaluation/In an environment: Difference between revisions

Content added Content deleted
(revert Tcl: insofar as I understand the Tcl, the old version was closer to correct, and I understand the change was an attempt to comply with my task req changes)
(→‎{{header|Tcl}}: this imitates other examples (right?))
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=={{header|Tcl}}==
=={{header|Tcl}}==

{{incorrect|Tcl|The code provided should not itself be a function, but have x as a free variable.}}


<lang tcl>package require Tcl 8.5
<lang tcl>package require Tcl 8.5


proc eval_twice {func a b} {
proc eval_twice {func a b} {
set 1st [apply $func $a]
set x $a
set 2nd [apply $func $b]
set 1st [expr $func];
set x $b
set 2nd [expr $func];
expr {$2nd - $1st}
expr {$2nd - $1st}
}
}


eval_twice {x {expr {2 ** $x}}} 3 5 ;# ==> 24</lang>
puts [eval_twice {2 ** $x} 3 5];</lang>
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