sfeng/lisp-interpreter-rb
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beautify calc

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vonhyou 2021-04-12 20:14:55 +08:00
parent 30d16d5b12
commit 2aa2758d05
1 changed files with 15 additions and 11 deletions
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26
minlisp.rb
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@ -59,19 +59,21 @@ end
def generate_env def generate_env
lisp_env = { lisp_env = {
'+': ->(arr) { arr.sum }, # args.inject(0, :+) '+': ->(args) { args.sum }, # args.inject(0, :+)
'-': ->(*args) { eval args.join('-') }, '-': ->(*args) { eval args.join('-') },
'*': ->(*args) { eval args.join('*') }, '*': ->(*args) { eval args.join('*') },
'/': ->(*args) { eval args.join('/') }, '/': ->(*args) { eval args.join('/') },
'>': ->(x, y) { x > y }, '>': ->(args) { args[0] > args[1] },
'<': ->(x, y) { x < y }, '<': ->(args) { args[0] < args[1] },
'=': ->(x, y) { x == y }, '=': ->(args) { args[0] == args[1] },
'>=': ->(x, y) { x >= y }, '>=': ->(args) { args[0] >= args[1] },
'<=': ->(x, y) { x <= y }, '<=': ->(args) { args[0] <= args[1] },
'min': ->(*args) { args.min }, 'min': ->(*args) { args.min },
'max': ->(*args) { args.max }, 'max': ->(*args) { args.max },
'car': ->(arr) { arr[0] }, 'car': ->(arr) { arr[0] },
'cdr': ->(arr) { arr[1..-1] } 'cdr': ->(arr) { arr[1..-1] },
'print': ->(arg) { p arg },
'begin': ->(*args) { true }
} }
end end
@ -83,8 +85,6 @@ end
# p lisp_env[:car].call [1, 2, 3] # p lisp_env[:car].call [1, 2, 3]
# p lisp_env[:cdr].call [1, 2, 3] # p lisp_env[:cdr].call [1, 2, 3]
def do_sth ; end
##### Lisp Eval ##### Lisp Eval
def lisp_eval(elem, env = generate_env) def lisp_eval(elem, env = generate_env)
@ -93,9 +93,12 @@ def lisp_eval(elem, env = generate_env)
elsif elem.instance_of?(Integer) || elem.instance_of?(Float) elsif elem.instance_of?(Integer) || elem.instance_of?(Float)
elem elem
elsif elem[0] == :def elsif elem[0] == :def
do_sth _, sym, exp = elem
env[sym] = lisp_eval(exp, env)
elsif elem[0] == :if elsif elem[0] == :if
do_sth _, cod, if_true, if_false = elem
exp = lisp_eval(cod, env) ? if_true : if_false
lisp_eval exp, env
else else
args = [] args = []
elem[1..-1].each { |arg| args << lisp_eval(arg, env) } elem[1..-1].each { |arg| args << lisp_eval(arg, env) }
@ -106,3 +109,4 @@ end
# p lisp_eval(parse '(/ (+ 1 (* 2 3) 1 1 (+ 1 (- 7 2) 1)) 4)') # p lisp_eval(parse '(/ (+ 1 (* 2 3) 1 1 (+ 1 (- 7 2) 1)) 4)')
lisp_eval(parse '(begin (def var1 7) (print (if (> var1 1) (+ 1 30) (- 10 2))))')