hlc's Introduction

HLC

Henry's Lambda Calculus.

I envison HLC to inhabit some of the stylistic choices in programming languge design, which also being completely true to the assignment (hw06).

Grammar

The grammar for HLC is the following:


  <program> ::=
  | Module <name> { *<statement> }
  | Executable <name> { *<statement> } Main { <expression> }
  | Main { <expression> }

  <statement> ::=
  | Definition <name> := { <expression> }

  <expression> ::=
  | <primitive>
  | <variable>
  | <name> => <expression>                  # lambda
  | <expression> <expression>               # application
  | <name> := <expression> ; <expression>   # binding
  | ( <expression> )                        # association

  <primitive> ::=
  | unit                                    # unit
  | true | false                            # booleans
  | <natural>                               # naturals 0,1,2,...
  | +<natural> | -<natural>                 # integers

  <variable> ::= <name>

  <name> ::= <string>

Note the following conventions:

*pattern is a possibly-empty list of pattern

Running

To run HLC on a program, do

  make run source=<source.hlc>

If the program has a Main, the Main body will be normalized then output.

For example, to run the program in examples/sample1.hlc, do

  make run source=examples/sample.hlc

To toggle verbosity, do

  make run source=<source.hlc> verbosity=<level>

where the verbosity levels are

level	description
0	output,
1	warnings
2	notes
3	logs

Organization

Building

The behind-the-scenes process for building and running HLC is the following:

ml-build gathers the sml source files, as specified by hlc.cm
ml-build builds a heap image main.amd64-darwin
sml @SMLload main.amd64-darwin <source.hlc> runs the main function specified in main.sml, passing <source.hlc> as an argument

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