jdh30’s gists

jdh30 / dfs.fs

Created April 4, 2017 16:56

Imperative and purely functional depth-first searches in F#

	open System.Collections.Generic

	/// Imperative depth-first search
	let dfs (V, E) =
	let visited = HashSet(HashIdentity.Structural)
	let stack = Stack[V]
	while stack.Count > 0 do
	let u = stack.Pop()
	if not(visited.Contains u) then
	for v in E u do

jdh30 / j.c

Created April 6, 2017 01:01

Arthur Whitney's mini J interpreter in C from "Remembering Ken Iverson" http://keiapl.org/rhui/remember.htm

	typedef char C;typedef long I;
	typedef struct a{I t,r,d[3],p[2];}*A;
	#define P printf
	#define R return
	#define V1(f) A f(w)A w;
	#define V2(f) A f(a,w)A a,w;
	#define DO(n,x) {I i=0,_n=(n);for(;i<_n;++i){x;}}
	I ma(n){R(I)malloc(n4);}mv(d,s,n)I d,*s;{DO(n,d[i]=s[i]);}
	tr(r,d)I d;{I z=1;DO(r,z=zd[i]);R z;}
	A ga(t,r,d)I *d;{A z=(A)ma(5+tr(r,d));z->t=t,z->r=r,mv(z->d,d,r);

jdh30 / bf.bf

Created April 6, 2017 01:03

BF interpreter written in BF from "A very short self-interpreter" https://arxiv.org/html/cs/0311032

jdh30 / FemtoMLParserUsingFParsec.fs

Last active June 6, 2020 03:48

FemtoML parser in F# using FParsec

	> let pInt : Parser<_, unit> = puint32 \|>> int .>> spaces;;

	> let str s = pstring s >>. spaces;;

	> let keywords =
	"if then else let rec in fun".Split ' '
	\|> set;;

	> let pIdent : Parser<_, unit> =

jdh30 / FemtoMLParserUsingFSLexAndYacc.fs

Created April 15, 2017 22:06

FemtoML parser in F# using fslex and fsyacc

jdh30 / FemtoMLParserUsingActivePatterns.fs

Last active May 22, 2019 05:12

FemtoML parser in F# using active patterns

	> let alpha = set['a'..'z'] + set['A'..'Z'];;

	> let num = set['0'..'9'];;

	> let alphanum = alpha + num;;

	> let (\|Char\|_\|) alphabet = function
	\| c::cs when Set.contains c alphabet -> Some(c, cs)
	\| _ -> None;;

jdh30 / ConcestorMap.fs

Created October 9, 2017 19:54

Persistent Map implemented as a Concestor data structure

	// This code implements a persistent dictionary similar to Map except the
	// internal representation is a Dictionary + diffs. This offers different
	// performance tradeoffs and, in particular, much faster add and remove when
	// used linearly.
	//
	// For more details, see the following articles from the F# Journal:
	//
	// http://fsharpnews.blogspot.co.uk/2017/10/the-concestor-set.html
	// http://fsharpnews.blogspot.co.uk/2017/10/a-simple-concestor-dictionary.html

jdh30 / InstallOCaml.sh

Last active September 28, 2024 10:30

Script to install and initialize OCaml for microservice development (TCP+HTTP+JSON) on an Ubuntu Linux box (e.g. in Amazon's AWS Cloud)

	sudo apt-get update
	sudo apt-get install opam elpa-tuareg make m4 gcc zip aspcud emacs libssl-dev ncurses-dev pkg-config libffi-dev bubblewrap linux-tools-common linux-tools-aws
	opam init
	eval $(opam env --switch=default)
	opam install ocamlfind core async async_ssl cohttp yojson ppx_deriving ocp-indent merlin cohttp-async ocamlformat utop

jdh30 / deriv.swift

Last active March 11, 2024 14:49

Swift code to compute the nth derivative of x^x

	enum Expr {
	case Int(n: Int)
	case Var(x: String)
	indirect case Add(f: Expr, g: Expr)
	indirect case Mul(f: Expr, g: Expr)
	indirect case Pow(f: Expr, g: Expr)
	indirect case Ln(f: Expr)
	}

	func pown(a: Int, b: Int) -> Int {

jdh30 / deriv.ml

Created December 24, 2017 04:13

OCaml code to compute the nth derivative of x^x

Jonathan Harrop jdh30