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@niku
Last active August 29, 2015 14:04
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すごいErlangゆかいに学ぼうの15ページ(内包表記)の例について
# "税込み(たとえば7%)で$3 から$10 の間に収まるような料理の価格をすべて見たい" は
# "税抜きで$3 から$10 の間に収まるような料理の価格をすべて税込み(たとえば7%)で見たい" の方が適切な印象です.
# 例えば 3 番目の式を
# "税込み(たとえば7%)で$3.6 から$10 の間に収まるような料理の価格をすべて見たい"
# と解釈すると poutine が含まれるはずです.
/Users/niku% erl
Erlang/OTP 17 [erts-6.1] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false] [dtrace]
Eshell V6.1 (abort with ^G)
1> RestaurantMenu = [{steak, 5.99}, {beer, 3.99}, {poutine, 3.50}, {kitten, 20.99}, {water, 0.00}].
[{steak,5.99},
{beer,3.99},
{poutine,3.5},
{kitten,20.99},
{water,0.0}]
2> [{Item, Price*1.07} || {Item, Price} <- RestaurantMenu, Price >= 3, Price =< 10].
[{steak,6.409300000000001},{beer,4.2693},{poutine,3.745}]
3> [{Item, Price*1.07} || {Item, Price} <- RestaurantMenu, Price >= 3.6, Price =< 10].
[{steak,6.409300000000001},{beer,4.2693}]
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