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Mark Di Marco

@markmarkoh.bsky.social

Early stage startup engineer and engineering leader, currently VP of Eng at Buildforce.

Recording episodes of a new show called Commit History, which explores interesting commit on interesting open source projects

https://markmarkoh.com

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Mark Di Marco @markmarkoh.bsky.social · Nov 13

I’m looking for interesting open source projects to do an episode of my show on!

Mark Di Marco

@markmarkoh.bsky.social

`lt` has been a fun toy project. I doubt the population of TUI enthusiasts and Linear.app users is very big, but the point of the project was to build something for me, and learn some #rust along the way.

July 16, 2025 at 1:50 PM

Mark Di Marco

@markmarkoh.bsky.social

Is this vibe coding? Asking for a friend.

April 12, 2025 at 12:26 AM

Mark Di Marco

@markmarkoh.bsky.social

I put together a website that lets you compare programming language features across multiple languages: dialectical.dev

I’ve got Zig, Rust, Nim, Python, Kotlin, Typescript, Elixir, Go, and Gleam in there.

LMK if I should add anything else! Language concept or language.

Programming Language Comparison

Compare programming concepts across different languages

dialectical.dev

April 10, 2025 at 5:12 PM

Mark Di Marco

@markmarkoh.bsky.social

It was fun to see how v8 (and this @nodejs.org and @chromium.social and co) added optional chaining (?.) to the language. Just ~250 lines of code to get the initial version in!

open.substack.com/pub/commithi...

ep9 v8: Initial implementation of optional chaining ⛓️‍💥

A quick tour through compiler design to see how v8 implemented optional chaining in Javascript

open.substack.com

January 12, 2025 at 2:56 PM

Reposted by Mark Di Marco

Marco Ippolito

@marcoippolito.dev

Node.js v23.6.0 is out! 🥳🎉

This release enables the flag --experimental-strip-types by default.

Node.js will be able to execute TypeScript files without additional configuration!

⚠️ This feature is experimental, has limitations and is subject to change.

nodejs.org/en/blog/rele...

Node.js — Node v23.6.0 (Current)

Node.js® is a JavaScript runtime built on Chrome's V8 JavaScript engine.

nodejs.org

January 7, 2025 at 5:56 PM

Mark Di Marco

@markmarkoh.bsky.social

The Day 1 #AdventOfCode solution we've all been waiting for: COBOL

65 years ago a committee met in the Pentagon to standardize a new programming language, and soon COBOL-60 was born.

Can you guess the name of the sorting algorithm used in the SORT-ARRAYS procedure?

adventofcode.com/2024/day/1

Screenshot of code Preamble in COBOL:
IDENTIFICATION DIVISION.
PROGRAM-ID. NUMBER-PAIRING.

ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT INPUT-FILE ASSIGN TO "INPUT.TXT"
ORGANIZATION IS LINE SEQUENTIAL.

DATA DIVISION.
FILE SECTION.
FD INPUT-FILE.
01 INPUT-LINE.
05 LEFT-NUM PIC X(5).
05 FILLER PIC X(3).
05 RIGHT-NUM PIC X(5).

WORKING-STORAGE SECTION.
01 WS-ARRAYS.
05 LEFT-ARRAY OCCURS 1000 TIMES PIC S9(5).
05 RIGHT-ARRAY OCCURS 1000 TIMES PIC S9(5).

01 WS-VARIABLES.
05 EOF-FLAG PIC X VALUE 'N'.
05 ARRAY-SIZE PIC 9(4) VALUE 0.
05 TOTAL-DIST PIC 9(8) VALUE 0.
05 TEMP-NUM PIC S9(5).
05 I PIC 9(4).
05 J PIC 9(4).
05 DIFF PIC S9(5).

PROCEDURE DIVISION.
MAIN-PROCEDURE.
DISPLAY "=== STARTING PROGRAM ==="
OPEN INPUT INPUT-FILE
PERFORM READ-NUMBERS UNTIL EOF-FLAG = 'Y'
CLOSE INPUT-FILE

DISPLAY "=== SORTING ARRAYS ==="
PERFORM SORT-ARRAYS

DISPLAY "=== CALCULATING DISTANCES ==="
PERFORM CALCULATE-DISTANCE

DISPLAY "=== FINAL RESULT ==="
DISPLAY "TOTAL DISTANCE: " TOTAL-DIST
STOP RUN.

Screenshot of main procedures in COBOL for day 1 of advent of code solution:
READ-NUMBERS.
READ INPUT-FILE
AT END MOVE 'Y' TO EOF-FLAG
NOT AT END
ADD 1 TO ARRAY-SIZE
MOVE FUNCTION NUMVAL(LEFT-NUM) TO LEFT-ARRAY(ARRAY-SIZE)
MOVE FUNCTION NUMVAL(RIGHT-NUM) TO RIGHT-ARRAY(ARRAY-SIZE)
END-READ.

SORT-ARRAYS.
PERFORM VARYING I FROM 1 BY 1
UNTIL I > ARRAY-SIZE - 1
PERFORM VARYING J FROM 1 BY 1
UNTIL J > ARRAY-SIZE - I
IF LEFT-ARRAY(J) > LEFT-ARRAY(J + 1)
MOVE LEFT-ARRAY(J) TO TEMP-NUM
MOVE LEFT-ARRAY(J + 1) TO LEFT-ARRAY(J)
MOVE TEMP-NUM TO LEFT-ARRAY(J + 1)
END-IF
IF RIGHT-ARRAY(J) > RIGHT-ARRAY(J + 1)
MOVE RIGHT-ARRAY(J) TO TEMP-NUM
MOVE RIGHT-ARRAY(J + 1) TO RIGHT-ARRAY(J)
MOVE TEMP-NUM TO RIGHT-ARRAY(J + 1)
END-IF
END-PERFORM
END-PERFORM.

CALCULATE-DISTANCE.
PERFORM VARYING I FROM 1 BY 1
UNTIL I > ARRAY-SIZE
COMPUTE DIFF = LEFT-ARRAY(I) - RIGHT-ARRAY(I)
IF DIFF < 0
COMPUTE DIFF = DIFF * -1
END-IF
ADD DIFF TO TOTAL-DIST
END-PERFORM.

December 1, 2024 at 6:58 PM

Mark Di Marco

@markmarkoh.bsky.social

I look for commits in all sorts of programming languages, and so far throughout my research, Zig has been my favorite “new” language that not enough people are talking about.

Here were a few patterns from my Bun.sh episode that stuck out:

@ziglang.bsky.social

December 1, 2024 at 3:20 PM

Reposted by Mark Di Marco

Mike Bostock

@ocks.org

@fil.rezo.net and I are working on further improvements to the waffle mark, including better tooltips, better stroke, and a better default unit for very large or very small values. github.com/observablehq...

waffle tips + waffle stroke + waffle unit: auto by Fil · Pull Request #2215 · observablehq/plot

unit: auto (closes waffle unit: auto #2214) waffle tips #2132 (merge commit, closes Waffle mark tooltips are always on axis line #2129) waffle stroke #2204 (merge commit closes Waffle pattern doe...

github.com

November 20, 2024 at 8:47 PM

Mark Di Marco

@markmarkoh.bsky.social

The implementation of the waffle mark in @observablehq.com’s Plot library is a lot more elegant and clever than I thought it would be: open.substack.com/pub/commithi...

#javascript #dataviz

ep8 plot: waffle mark 🧇

Observable's data visualization library is full of fun little tricks, especially with this waffle mark commit

open.substack.com

November 19, 2024 at 2:25 PM

Mark Di Marco

@markmarkoh.bsky.social

A review of a fun small commit to the @zed.dev editor that had a huge performance boost - always fun digging into commits like these. open.substack.com/pub/commithi...