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author HackBot
date Sun, 09 Dec 2012 19:30:08 +0000
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1 Lambda calculus interpreter
2 (c) Nikita Ayzikovsky, 2006
3
4 Usage:
5
6 run lambda.py, which reads a single-line lambda calculus program from stdin.
7
8 Syntax:
9
10 A program can optionally contain any number of definitions, followed by
11 an expression.
12
13 Definitions are of the form
14
15 name = expression ;
16
17 Expressions are standard lambda calculus expressions, with the symbol lambda
18 denoted by \. E.g.
19
20 \x,y,z.(x (z y))
21
22 Don't forget to surround with brackets anything that ought to be surrounded
23 with brackets (any lambda body where something gets applied to something else)
24 "\x,y.x y" is an application of \x,y.x to y; but "\x,y.(x y)" is a single function
25 of two variables.
26
27 IO:
28
29 Input is not implemented.
30 For output, an expression of the form "text", when evaluated, prints 'text'
31 and evaluates to the identity function.
32 #show is a special function that evaluates its argument, and prints out
33 the result before returning it.
34 #list is a special expression that, when evaluated, prints the list of all
35 definitions.
36
37
38 DEFINITIONS:
39
40 Definitions ('name = exp;') are persistent between program runs. To get
41 rid of all definitions, remove the file defs.pickle.