Learn: Extending min
min provides a fairly complete standard library with many useful modules. However, you may feel the need to extend min in order to perform more specialized tasks.
In such situations, you basically have the following options:
- Implementing new min modules using min itself
- Specifying your custom prelude program
- Embedding min in your Nim program
Implementing new min modules using min itself
When you just want to create more high-level min operator using functionalities that are already available in min, the easiest way is to create your own reusable min modules.
To create a new module, simply create a file containing your operator definitions implemented using either the
operator operator or the
(dup *) ^pow2 (dup dup * *) ^pow3 (dup dup dup * * *) ^pow4
Save your code to a file (e.g. quickpows.min) and you can use it in other nim files using the
require operator and the
import (if you want to import the operators in the current scope):
'quickpows require :qp 2 \*qp/pow3 \*qp/pow2 puts ;prints 64
Specifying your custom prelude program
By default, when min is started it loads the following prelude.min program:
; Imports 'str import 'io import 'logic import 'num import 'sys import 'stack import 'seq import 'dict import 'time import 'fs import 'lite? ( ( 'crypto import 'math import 'net import 'http import ) ROOT with ) unless ; Unseal prompt symbol 'prompt unseal-symbol
Essentially, this causes min to import all the modules (except for some if the lite flag was defined at compilation time) and unseals the
prompt symbol so that it can be customized. If you want, you can provide your own prelude file to specify your custom behaviors, selectively import modules, and define your own symbols, like this:
$ min -i -p:myfile.min
Embedding min in your Nim program
If you’d like to use min as a scripting language within your own program, and maybe extend it by implementing additional operators, you can use min as a Nim library.
To do so:
- Install min sources using Nifty as explained in the Download section.
- Import it in your Nim file.
- Implement a new
procto define the module.
The following code is taken from HastySite and shows how to define a new
hastysite module containing some symbols (
import min proc hastysite_module*(i: In, hs1: HastySite) = var hs = hs1 let def = i.define() def.symbol("preprocess") do (i: In): hs.preprocess() def.symbol("postprocess") do (i: In): hs.postprocess() def.symbol("process-rules") do (i: In): hs.interpret(hs.files.rules) # ... def.finalize("hastysite")
Then you need to:
- Instantiate a new min interpreter using the
- Run the
procused to define the module.
- Call the
interpretmethod to interpret a min file or string:
proc interpret(hs: HastySite, file: string) = var i = newMinInterpreter(file, file.parentDir) i.hastysite_module(hs) i.interpret(newFileStream(file, fmRead))
For more information on how to create new modules with Nim, have a look in the lib folder of the min repository, which contains all the min modules included in the standard library.