λtext

General-Purpose Templating Utility

Overview

λtext turns text files into higher-order functions, featuring a Hindley-Milner / prenex polymorphic type system.

Installation

$> cabal install ltext

Usage

You can supply options manually with flags:

$> ltext --help

ltext - higher-order file applicator

Usage: ltext EXPRESSION [-t|--type] [-o|--output OUTPUT] [-l|--left LEFTDELIM]
             [-r|--right RIGHTDELIM] [-c|--config CONFIG]
  Evaluate EXPRESSION and send to OUTPUT

Available options:
  -h,--help                Show this help text
  -t,--type                query the type signature of an expression
  -o,--output OUTPUT       output destination
  -l,--left LEFTDELIM      left delimiter
  -r,--right RIGHTDELIM    right delimiter
  -c,--config CONFIG       location of config file

# as an example
$> ltext "foo bar" --left "{{" --right "}}" -o "baz"

or, you can store commonly used ones in a YAML file under ./.ltext/config.yaml:

$> cat ./.ltext/config.yaml

typeQuery: false
left: "//{{"
right: "}}"

$> cat foo

## x ##

asdf
birds

## x ##

fsda

# keeping delimiters in-line
$> ltext "foo"

//{{ x }}

asdf
bird

//{{ x }}

fsda

$> cat bar

hashtagtrashswag

# application
$> ltext "foo bar"

hashtagtrashswag

asdf
bird

hashtagtrashswag

fsda

How It Works

From λtext's point of view, any file can be a template. Just declare parameters in your files (usually in a different syntax than the file's native tongue, via comments or obscure delimiters), use those variables somewhere in the content, then with the ltext command you apply the function-y files to each other.

The CLI

There will be two primary uses of the ltext command - evaluating template expressions, and querying for the type signature of a template/expression.

Expression Evaluation

When we evaluate a template expression, normally we just feed the result to stdout. But there is also the -o flag, for explicitly stating an output file.

Note: all output from ltext will be UTF-8.

Type Queries

Just like the :t command in GHCi, you can find out the type of a template or expression with -t.

Variable Recognition

When we use a parameter in a file, we need it to be easily recognized by a parser - either a different syntax than to the language you're working with - an explicit delimitation.

The first line in a file will be tested against to see if it qualifies as a lambda header. If you don't want a file have recognized arity, just throw in a newline.