This package implements the lambda calculus using interaction nets, providing CLI and API.
Its browserified version is available as an online demo.
The following encodings of the lambda calculus are included:
closed, the approach of arXiv:1304.2290 applied to An Interaction Net Implementation of Closed Reduction by Ian Mackie;
optimal, an implementation of Lambdascope by Vincent van Oostrom et al;
standard, an implementation of optimal reduction as in The Optimal Implementation of Functional Programming Languages, pp. 40-41.
The embedded read-back mechanism is described in Section 7 of 10.4204/EPTCS.225.7.
The following is output of the
test.sh script provided in the package:
SAMPLE ABSTRACT CLOSED OPTIMAL STANDARD counter N/A 162/25 582/14 2322/14 w2eta 37/7 137/16 207/7 374/7 1021 199/55 11871/1088 1599877/55 4307803/55 22210i 494/68 2539/254 58603/68 N/A 3222i 1206/50 8638/819 804530/50 N/A 1022i 4317/69 33369/3139 N/A N/A 2222101 2621862/327818 N/A N/A N/A facty6nt 1112/210 80562/2436 2790152/210 3013433/210 facty9i 1629/287 3746232/130949 N/A N/A 33-fact4 3770/704 16114/912 80708/704 234075/704 fibo16nt 24931/3042 134135/5673 5462375/3042 8959455/3042 fact100i 28502/3752 121854/10565 N/A N/A 35-fact5 72944/13480 805218/16206 4702711/13480 N/A fibo20i 93534/6863 536843/24626 1961508/6863 4023117/6863 fact1knt 6215039/1353692 N/A N/A N/A
T/B should be read as total of
B were β-reductions.
This package provides the
lambda command with the following interface:
Usage: lambda [options] (<term> | -f <file>) Options: --algo, -a Select algorithm [string] --debug, -d Evaluate step by step [boolean] --exec, -e Process m4(1) macros [boolean] --file, -f Read term from file [boolean] --inet, -i Show interaction net [boolean] --limit, -l Limit interactions [number] --macros, -m Read macros from file [string] --perf, -p Print benchmarks [boolean] --stats, -s Save statistics to file [string] --term, -t Output expanded term [boolean] --help, -h Show help [boolean] --version, -v Show version number [boolean]
CLI predefines a number of commonly used combinators:
# Common combinators I = x: x; K = x, y: x; S = x, y, z: x z (y z); Y = (a: a a) (a, f: f (a a f)); # Booleans T = K; F = K I; Not = p, a, b: p b a; And = p, q: p q F; Or = p, q: p T q; Xor = p, q: p Not I q; # Pairs/lists  = K T; ? = l: l (h, t: F); Cons = h, t, x: x h t; Head = l: l T; Tail = l: l F; # Church arithmetic +1 = n, f, x: f (n f x); + = m, n, f, x: m f (n f x); * = m, n, f: m (n f); ^ = m, n: n m; -1 = n, f, x: n (g, h: h (g f)) (K x) I; - = m, n: n -1 m; 0? = n: n (K F) T; # Church numerals 0 = f, x: x; 1 = f, x: f x; 2 = +1 1; 3 = +1 2; 4 = ^ 2 2; 5 = + 2 3; 6 = * 2 3; 7 = +1 6; 8 = ^ 2 3; 9 = ^ 3 2; 10 = * 2 5; 16 = ^ 2 4; 20 = * 2 10; 30 = * 3 10; 32 = ^ 2 5; 64 = ^ 2 6; 100 = ^ 10 2; 128 = ^ 2 7; 256 = ^ 2 8; 512 = ^ 2 9; 1k = ^ 10 3; 1ki = ^ 2 10; 1m = ^ 10 6; 1mi = ^ 2 20; 1g = ^ 10 9; 1gi = ^ 2 30; # Recursive functions FactY = Y (f, n: (0? n) 1 (* (f (-1 n)) n)); Fact = n: n (f, i: * (f (+1 i)) i) (K 1) 1; Fibo = n: n (f, a, b: f (+ a b) a) F 1 0;
require("@alexo/lambda") returns a function of a lambda term defined
in a variant of the lambda calculus called Macro Lambda Calculus (MLC)
that allows macro definitions in order to input complex expressions.
The last term in the input is the term whose normal form is to be found.
For developing and testing purposes, the package also exports
two additional functions
.debug() function applies a single reduction step to
the interaction net compiled by the previous
call and returns a human-readable string representation of
the current interaction net state.
Input consists of an optional list of macro definitions and a term:
%token NAME %% text : defs term ; defs : /* empty */ | defs NAME '=' term ';' ; term : appl | abst ; abst : NAME ',' abst | NAME ':' term ; appl : atom | appl atom ; atom : '(' term ')' | NAME ;
Copyright (c) 2017 Anton Salikhmetov
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