55 lines
1.8 KiB
JavaScript
55 lines
1.8 KiB
JavaScript
const ZERO = f => x => x;
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const ONE = f => x => f(x);
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const TWO = f => x => f(f(x));
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const THREE = f => x => f(f(f(x)));
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const TIMES = n => f => x => n(f)(x);
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const INC = n => f => x => f(n(f)(x));
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const ADD = n => m => n(INC)(m);
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const MULT = n => m => n(ADD(m))(ZERO);
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const POWER = n => m => n(MULT(m))(ONE);
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// DEC is stolen from PRED here:
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// https://en.wikipedia.org/wiki/Lambda_calculus#Arithmetic_in_lambda_calculus
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const DEC = n => f => x => n(g => h => h(g(f)))(y => x)(y => y);
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const SUB = n => m => m(DEC)(n);
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const TRUE = x => y => x;
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const FALSE = x => y => y;
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const IF = b => b;
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const NOT = b => IF(b)(FALSE)(TRUE);
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const AND = a => b => IF(a)(IF(b)(TRUE)(FALSE))(FALSE);
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const OR = a => b => IF(a)(TRUE)(IF(b)(TRUE)(FALSE));
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const IS_ZERO = n => n(x => FALSE)(TRUE);
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const IS_LEQ = n => m => IS_ZERO(SUBTRACT(n)(m)); // we only have positive ints
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const IS_EQ = n => m => AND(IS_LEQ(n)(m))(IS_LEQ(m)(n)); // this is stupid
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// time to get recursive!
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const Y = f => (x => f(x(x)))(x => f(x(x))); // lazy recursion
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const Z = f => (x => f(_ => x(x)(_)))(x => f(_ => x(x)(_))); // eager recursion
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const FACT = Z(f => n => IF(IS_ZERO(n))(ONE)(_ => MULT(n)(f(DEC(n)))(_)));
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const DIV = null;
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const MOD = null;
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const PAIR = null;
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const LEFT = null;
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const RIGHT = null;
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const EMPTY = null;
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const UNSHIFT = null;
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const IS_EMPTY = null;
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const FIRST = null;
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const REST = null;
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const INJECT = null;
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const FOLD = null;
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const MAP = null;
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const RANGE = null;
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const SUM = null;
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const PROD = null;
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const CONCAT = null;
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const PUSH = null;
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const REVERSE = null;
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const INC_ALL = null;
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const DOUBLE_ALL = null;
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const TO_DIGITS = null;
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const TO_STRING = null;
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const FIZZBUZZ = null;
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module.exports = {
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ZERO, ONE, TWO, THREE, TIMES, INC, ADD, MULT, POWER, DEC, SUB, TRUE,
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FALSE, IF, NOT, AND, OR, IS_ZERO, IS_LEQ, IS_EQ, IS_LEQ, Y, Z, FACT
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};
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