const { Stack } = require('@hypercubed/f-flat@0.0.6');
const f = new Stack();
f.eval(`
core: rcl use
math: rcl use
types: rcl use
shuffle: rcl use
`).stack;
First we define lambda helpers.
`=>` Stores values from the stack into each name in the list. For example `1 2 3 [ x: y: ] =>` assigns 2 to x and 3 to y, leaving 1 on the stack.
`lambda-eval` evaluates a lamba in the form of `[ [ args ] => expression ]`. Notice the use of `fork`. Since the vocabulary is write-once, this executes the expression on a child stac, and therefore prevents polluting the local vocab.
Finally, `lambda` converts an expression to a lambda expression.
f.eval(`
=>: [ [ sto ] [ reverse ] dip foreach ] ;
lambda-eval: [
[ stack ] dip
unstack: swap >>
>> fork unstack
] ;
lambda: [
[ lambda-eval ] >>
] ;
`).stack;
Where we define the quadratic equation using lambdas (formulation from https://www.reddit.com/r/concatenative/comments/35xpxv/ltu_concatenative_language_kont/cr9ixmb/)
f.eval(`
quad: [
[ 'a' 'b' 'c' ] =>
b -1 * b b * 4 a c * * - sqrt -+
[ 2 a * / ] bi@
] lambda ;
`).stack.toString();
And to test:
f.eval(`
\`The roots of 2x^2+5x-3 are $(2 5 -3 quad)\`
`).stack.toString();
f.eval(`
clr
\`The roots of 1x^2+5x-1 are $(1 1 -1 quad)\`
`).stack.toString();
f.eval(`
clr
\`The roots of 2x^2+3x+4 are $(2 3 4 quad)\`
`).stack.toString();
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