https://github.com/redprl/sml-typed-abts
second-order abstract syntax
https://github.com/redprl/sml-typed-abts
abstract-syntax binding syntax
Last synced: 2 months ago
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second-order abstract syntax
- Host: GitHub
- URL: https://github.com/redprl/sml-typed-abts
- Owner: RedPRL
- Created: 2015-09-25T04:42:41.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2021-09-15T22:47:00.000Z (over 3 years ago)
- Last Synced: 2025-01-08T08:40:04.894Z (4 months ago)
- Topics: abstract-syntax, binding, syntax
- Language: Standard ML
- Homepage:
- Size: 353 KB
- Stars: 31
- Watchers: 15
- Forks: 9
- Open Issues: 10
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
### sml-typed-abts
This is an implementation of Abstract Binding Trees from [Robert
Harper](https://www.cs.cmu.edu/~rwh/)'s book, [Practical Foundations for
Programming Languages](https://www.cs.cmu.edu/~rwh/plbook/2nded.pdf).
In particular, this differs from many implementations of ABTs in the following
respects:
- Unlike Nuprl-style ABTs, this is a library for *many-sorted* abstract binding
trees.
### Getting Started
#### Prerequisites
You need either SML/NJ or MLton. Either [download the binary SML/NJ
installer](http://www.smlnj.org/) or, on OS X, use homebrew:
brew update && brew install smlnj
#### Downloading the repository
Recursively clone the repo:
git clone --recursive https://github.com/jonsterling/sml-typed-abts.git
Note: whenever you pull anew from this repository, be sure to refresh the
submodules:
git submodule update --init --recursive
#### Running the example with MLton
To run the example with MLton, use the included script, and then run the
resulting executable:
./scripts/mlton.sh
./example.out
Eventually, a prompt should appear at which you can parse and sort-check/infer
ABT expressions. Here's an example session:
Type an expression at the prompt
> \x. x
lam([x@10].x@10)
> (\f. f 3) (\x. x)
Error: Fail: expected exp == nat
> (\f. f #3) (\x. x)
ap(lam([f@31].ap(f@31; num(3))); lam([x@32].x@32))
The printer is in "debug mode", which means that all variables are
annotated with a unique index; this is useful for convincing oneself that
variables are being bound properly.
#### Running the example in SML/NJ
Start the SML REPL:
cd sml-typed-abts
rlwrap sml
Standard ML of New Jersey v110.78 [built: Sun Apr 26 01:06:11 2015]
-
At the `-` prompt, type:
- CM.make "example.cm";
You should see a lot of compilation messages and then, the prompt should
appear:
Type an expression at the prompt
>