What would I do? I'd use this opportunity to practice adverbial
programming. (Yes, thank you, I've learned from your answers to my
tacit adverb questions.) I've changed your definition of clear so that y
sets the initial stack, and of dup. All of the j stack manipulation
verbs are monadic. Excepting clear, enter, and dupkip, they ignore y.
To do: handle errors, write an interpreter, other.
Stack =: 1 : ' ,.STACK =: ((STACK"_) :: (''''"_) 0) u y'
NB. u Monad replaces top of stack with u TOS
Monad =: (@:{:)(]`}:`,`)(`:6)~ Stack
NB. u Dyad replaces top 2 items with the
NB. result of inserting u between them.
Dyad =: (/)(]`(_2&}.)`,`[:`)(`(_2&{.))(`:6)~ Stack
clear =: ] Stack
enter =: , Stack
dupkip =: ([ , ({.~ -)) Stack
rot3 =: ((_3 }. [) , _1 |. _3 {. [) Stack
dup =: 2&# Monad
reciprocal =: % Monad
chs =: - Monad
plus =: + Dyad
minus =: - Dyad
times =: * Dyad
divide =: % Dyad
exch =: ,~ Dyad
clear'eta'
e
t
a
exch''
e
a
t
rot3''
t
e
a
enter'm'
t
e
a
m
clear i.8
0
1
2
3
4
5
6
7
reciprocal''
0
1
2
3
4
5
6
0.142857
divide''
0
1
2
3
4
5
42
square =: times@dup NB. or *: Monad
square''
0
1
2
3
4
5
1764
Date: Thu, 5 Jun 2014 00:45:40 -0500
From: Kip Murray<[email protected]>
To:"[email protected]" <[email protected]>
Subject: [Jprogramming] rpn calculator
Message-ID:
<CAOfWorgKZnCkZtgFd6L6=_6nmquuhbyot0usypwatygf6b+...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
The following emulates a simple reverse Polish notation calculator which
operates on numbers at the bottom of a stack, replacing them by the result.
How would you do it? (Beware of line wrap.)
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