SML on macOS

Standard ML on macOS

• I completed Programming Languages, Part A by Dan Grossman from University of Washington.
• In Part A, Dan taught us many programming language concepts using Standard ML (SML)
• Dan is a great teacher and this course definitely deserves 5 stars.

SML Installation

• Installing SML/NJ in macOS (recommend using homebrew): https://smlnj.org/dist/working/110.96/macos.html

brew cask install smlnj

• Remember to export the path to SML in bash/zsh:

export PATH=$(brew --prefix)/smlnj/bin:"$PATH"

My REPL-like SML development environment

• I am too lazy to memorize those Emasc keyboard shortcuts so I decided to create a REPL-like environment by myself. See steps below:
• Install Visual Studio Code: https://code.visualstudio.com
• Install Standard ML plugin (not perfect but it works): https://marketplace.visualstudio.com/items?itemName=freebroccolo.sml
• When you edit SML code in Visual Studio Code, also open a terminal (View -> Terminal) and enter sml (The SML/NJ interactive shell)
  • You can then load the SML file. For example: use "hw3test.sml";
  • Exit the shell by Ctrl+D

(Important) Tune your SML/NJ interactive shell:

• Note that SML/NJ interactive shell doesn’t support arrow keys so you can’t use up/down to cycle through the history. However, I found a stack overflow post and resolved it by socat

brew install socat

# Then in your .bach_profile or .zshrc, add this alias
alias sml='socat READLINE EXEC:sml'

Cool stuff I learned

• oneOf type (Option, List). Read more on this: https://reasonablypolymorphic.com/blog/protos-are-wrong/
• Dynamic scope (where a function is called) vs Lexical scope (where a function is defined), also learned it in R programming.
• That Java mutation example
• Pattern matching for function definitions (Function pattern)

Links

• SML Basis Library: https://smlfamily.github.io/Basis/overview.html