About Nim (Formerly Nimrod)

[kcvinu]

Hi all,
I would like to share some interesting stuff about the Nim programming language.
Nim compiles code to first C/C++/Obj-C/JS code and then use a C/C++/Obj-C/JS compiler to make executable.
Nim's syntax is much like python. But you can taste some pascal style in Nim.
Nim has a minimal support for object oriented programming. It uses Types for it. Here is the syntax

type myClass = ref object of RootObj   # an object lives in stack, a ref object lives in heap. 
    aMember : int
    anotherMember : string

The main work horse in Nim is "proc", a Nim version for function and sub. Another best feature i love in Nim is Uniform Function Call Syntax aka UFCS. Assume that you have a function like this.

proc aFunction(param1 : string, param2 : int, param3 : bool) : bool

Then you can call that function like this -

param1.aFunction(param2, param3)

Another plus points
1. Nim uses Garbage Collector
2. You can inherit a Nim class with "of" keyword.
3. You can use pragmas. for ex: "{. pure.}" is a pragma. If you use it with an enum, then you must use name of that enum whenever you use any element of that enum.
4. Nim uses a magical "result" variable in functions. "result" is automatically the function result. So you dont need to create and assign one.
5. Classes created with "ref" keyword are initializing with "new" keyword.
6. To declare a variable or a function as public, you just need to put an "*" sign after the identifier.

Here is a sample code to understand Nim style.

type
	aClass  = ref object of RootObj		# A base class
		intVar : int
		strVar : string
		
	aChildClass = ref object of aClass		# A child class which inherits from aClass
		aVar : int
		boolVar : bool
		
proc NewClass(iVar : int) : aClass = 	# Constructor of aClass. 
	result = new aClass									
	result.intVar = iVar
	result.strVar = "Hi I am aClass member"
	
proc NewChildClass() : aChildClass = 
	result = new aChildClass 									
	result.intVar = 500 				# Accessing base class member
	echo "Hi I am from child class"    # Printing some text
	
proc childMethod(me : aChildClass) : int =
	result = me.intVar		# Magical result variable.
	
#Usage of this classes.
var aBase = NewClass(62)		# var is the dim in Nim
var aChild = NewChildClass()
echo aChild.childMethod() 		# prints 500. See the UFCS is interesting...

[kcvinu]

Since, Nim compiles to C, we can make sure that our program will work as fast as C. Author of Nim says that Nim can create better C code than any human made C code. Some guys in Nim forum are discussing Nim's speed with when compiled to C and CPP. Well i am using only C compiling version, because thats the default compiling method.

This UFCS is not only Nim's feature. The "D" programming language also using this.

[Petr Schreiber]

Hi kcvinu,

thanks a lot for the quick introduction to the language - highly appreciated!


Petr

[John Spikowski]

IUP is a nice companion library for Nim GUI projects.

[kcvinu]

@Petr,
You're welcome.

@John Spikowski,
Is it ? I never tried it. In fact, i am making one with win api nim. There is guy named ward(forum name) made a huge library of win api wrapper. It's called "winim". With winim, its very easy to code win api functions. Here are some samples.

import GuiLib       '# My Gui Library header file. It contains all necessary modules.

'# This Application class will do the initial jobs such as getting the hInstance.
'# You can pass a string for your window class name. It's optional.
var app = Application("Window-Nim")

 
'# Forward declarations. 
proc OnFormCreate( e : eventArgs)
proc OnLoad( e : eventArgs)
proc OnNCCreate(e : eventArgs)
proc OnButtonClick( e : eventArgs)
proc OnButtonClick2( e : eventArgs)
proc b1OnMouseEnter( e : eventArgs)
proc OnClosing( e : eventArgs)
proc OnSetFocus( e : eventArgs)
proc OnKillFocus( e : eventArgs)
proc OnMouseLeave_cbt(e : eventArgs)
proc OnMouseMove_Cal(e : eventArgs)
proc OnClick_CustomBTN(e : eventArgs)



'# Creating an instance of a form class. We need to pass the Application object as parameter--
'# -- in order to get the hInstance and other stuff.
var Form1 = NewForm(app)

'# RegisterMsg is for handling wm_create msg. I can't find a better way to do this.
Form1.RegisterMsg(WM_CREATE, OnFormCreate)

'# Now we are creating the form. If you want to set the for properties, you can--
'# --set it like this.
'# Form1.posx = 150
'# Form1.posy = 200
'# Form1.width = 800
'# Form1.height = 600
'# Form1.text = "My Nim Window"
'# But i am using default values here.
Form1.CreateForm()

'# Create some control classes
var 
    b1, b2 = Button()
    lv = ListView()
    cal = Calendar()
    ud = UpDown()
    dtp = DateTimePicker()
    trb = TrackBar()
    red = RichEdit()
    cbt = CustomButton()

'# Here you can add handler functions to control events lile click, mouse move etc.
b1.AddHandler(b1.event.click, OnButtonClick)
b2.AddHandler(b2.event.click, OnButtonClick2)
b2.AddHandler(b2.event.mouseLeave, b2_OnMouseLeave)
b1.AddHandler(b1.event.mouseEnter, b1OnMouseEnter)
Form1.AddHandler(Form1.event.mouseRightUp, OnDblClk_Form1)
Form1.AddHandler(Form1.event.closing, OnClosing)
Form1.AddHandler(Form1.event.load, OnLoad)
Form1.AddHandler(Form1.event.setFocus, OnSetFocus)
Form1.AddHandler(Form1.event.killFocus, OnKillFocus)
cal.AddHandler(cal.event.mouseEnter, OnMouseMove_Cal)
red.AddHandler(red.event.mouseLeave, OnMouseLeave_Red)
cal.AddHandler(cal.event.mouseHover,OnMouseHover_Cal)
cbt.AddHandler(cbt.event.click, OnClick_CustomBTN)
cbt.AddHandler(cbt.event.mouseLeave, OnMouseLeave_cbt)

'# Now, we can set the control properties.
b2.posx =140
b2.posy = 10
b2.text = "My Button"
b2.width = 150
b2.font.name = "Calibri"    '# Tahoma is default
b2.font.size = 12

lv.posx = 350
lv.posy = 10
lv.width = 300

cal.posx = 350
cal.posy = 10

ud.posx = 350
ud.posy = 320

'# See, custom button class has so many color properties. 
cbt.posx= 350
cbt.posy= 220
cbt.text = "Owner Drawn BTN"
cbt.backColor = NewColor(80, 16, 44)    '# NewColor function receives RGB values and returns a COLORREFF
cbt.foreColor = NewColor(15, 15, 80)
cbt.hoverBackColor = cbt.backColor      
cbt.hoverForeColor = NewColor(238,20,49)
cbt.width = 200
cbt.height = 80

dtp.posx = 150
dtp.posy = 150

trb.posx = 150
trb.posy = 120

red.posx = 10
red.posy = 200

'# Now we can create our controls.
b1.CreateButton()
b2.CreateButton()
cal.CreateCalendar()
ud.CreateUpDown()
dtp.CreateDateTimePicker()
trb.CreateTrackBar()
red.CreateRichEdit()
cbt.CreateCustomButton()

# Let's display our form
Form1.ShowForm()

'# This is the main loop.
app.Run()


'# Now, these are the event handler function area.
'# Argument "e" is a structure. It contains all necessary elements to handle the--
'# --WndProc function

proc OnCreate( e : eventArgs)  =
    echo "Window created....."
    echo e.handle   '# e.handle is the window HWND

proc OnLoad( e : eventArgs) =
    echo "Window Loaded...."
    
proc OnButtonClick( e : eventArgs) =
    b2.text = "Changed Text"    

proc OnButtonClick2( e : eventArgs) =    
    msgBox("A Message")     

proc b1OnMouseEnter( e : eventArgs) =
    echo "Mouse entered on button 1"

proc b2_OnMouseLeave( e : eventArgs) =
    echo "Mouse leaved from Button 2"    

proc OnNCCreate( e : eventArgs) =    
    echo "NC CREATE handled"  

proc OnClosing( e : eventArgs) =
    echo "Form is closing..."    

proc OnSetFocus( e : eventArgs) = 
    echo "Form is in focus...."

proc OnKillFocus( e : eventArgs) = 
    echo "Form lost focus...."

proc OnMouseLeave_cbt(e : eventArgs) =
    echo "Mouse leaved from Custom button..."

proc OnMouseMove_Cal(e : eventArgs) = 
    echo "Mouse hovered over Calendar..."

proc OnMouseLeave_Red(e : eventArgs) =
    echo "Mouse leave from Rich Edit..."

'# End

[John Spikowski]

The ease of use and native cross platform (Windows and Gtk Linux) shared objects or static linking. It works well with interpreters via FFI and has a stepping callback loop.

Eros created a IUP example in thinBasic a while back.

[jack]

hello kcvinu
that code looks good, easy to read and figure out.
hope you won't mind this link to a MFC alternative I found, looks interesting to me https://www.codeproject.com/Articles...pc=Tight&fr=26

[kcvinu]

hello kcvinu
that code looks good, easy to read and figure out.
hope you won't mind this link to a MFC alternative I found, looks interesting to me https://www.codeproject.com/Articles...pc=Tight&fr=26

Hi, Thanks for the good words. Let me check the link. May i can learn a lot from that project. Thanks for the link