From: Tanaka Akira <akr@...17n.org>
Date: 2001-10-31T17:08:30+09:00
Subject: [ruby-list:32139] Re: call by name

In article <87bsioe0uu.wl@studly.priv.netlab.jp>,
  Shugo Maeda <shugo@ruby-lang.org> writes:

> > Haskell$B$O$<$s$<$sCN$i$J$$$N$G$9$,!"(BAlgol$B$N(Bcall by name$B$_$?$$$J$b(B
> > $B$N$G$7$g$&$+!#(B

$B$o$?$7$b$=$s$J$KCN$C$F$$$k$o$1$G$O$J$$$G$9$,!"@N!"A4A30c$&$8$c$J$$$+$H(B
$B;W$C$?;~$K$O!"(Bscope $B$N0c$$(B - lexical scope $B$+$I$&$+(B - $B$,5$$K$/$o$J$+$C(B
$B$?5$$,$7$^$9!#$?$V$s!"(BAlgol $B$N(B call by name $B$NNc$H$7$F(B Ruby $B$N(B
iterator $B$_$?$$$JNc$7$+CN$i$J$$$N$G!"(Blexical scope $B$@$H$=$NNc$r<B8=$G(B
$B$-$J$$$N$,5$$K$/$o$J$+$C$?M}M3$J5$$,$7$^$9!#(B

$B:#$+$i9M$($k$H!"(Bscope $B$N0c$$$rL5;k$7$F!"0z?tI>2A$N%?%$%_%s%0$@$1$r9M$((B
$B$l$P%^%/%m$b(B Algol $B$N(B call by name $B$b(B Haskell $BE*$J(B call by name $B$bF1$8(B
$B$h$&$J$b$N$J$N$+$bCN$l$^$;$s!#(B

> $B!&(Bcall by name$B$NJQ<o(B(?)$B$K(Bcall by need$B$H$$$&$b$N$,$"$k!#(B
> $B!&(Bcall by need$B$NJ}$O!"F1$8%5%s%/$,FsEY8F$S=P$5$l$?>l9g!"FsEYL\$O<B(B
>   $B:]$K7W;;$r9T$&Be$j$KA0$N7W;;7k2L$rJV$9!#(B
> $B!&(Blazy evaluation$B$O(Bcall by need$B$N$3$H$G$"$k!#(B
> 
> $B$N$h$&$KFI$a$^$9$1$I!"$3$NM}2r$O@5$7$$$G$7$g$&$+(B?

$B$$$$$s$8$c$J$$$G$7$g$&$+!#$?$@!"$I$3$^$GIaJWE*$JDj5A$O$h$/$o$+$j$^$;$s!#(B

> $B$=$l$G!"EDCf$5$s$,$*$C$7$c$kN.57$H$$$&$N$O!"(B
> 
> $B!&(BC$B$N%^%/%m$_$?$$$KE83+$7$F$7$^$&N.57(B
> $B!&0z?t$N;2>H$r!"%5%s%/$N8F$S=P$7$KJQ49$9$kN.57(B
> 
> $B$NFs$D$N$3$H$G$7$g$&$+(B?

$B<+J,$NCf$G@53N$KJ,N`$G$-$F$$$k$o$1$G$O$J$$$N$G!"$"$$$^$$$K$7$+Ez$($i$l(B
$B$J$$$N$G$9$,!"$=$N$h$&$J46$8$G$9!#(B
-- 
[$BEDCf(B $BE/(B][$B$?$J$+(B $B$"$-$i(B][Tanaka Akira]
$B!V$U$($m(B! $B$o$+$a$A$c$s:n@o$G$9$(C"=$B!W(B(Little Worker, $B7KM7@84](B)