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222 lines
4.0 KiB
Markdown
222 lines
4.0 KiB
Markdown
---
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language: Easylang
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contributors:
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- ["chkas", "https://github.com/chkas"]
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filename: easylang.el
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---
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**Easylang** is a simple programming language with built-in graphical functions and an easy-to-use and offline usable browser IDE. Its simple syntax and semantics make it well suited as a teaching and learning programming language. You can also use it to write graphical applications that you can embed in a web page.
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*Easylang* is statically typed and has as data types only strings and numbers (floating point), resizeable arrays of strings and numbers and arrays of arrays.
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[The browser IDE](https://easylang.online/ide/) includes various tutorials, including one for beginners.
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```
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print "Hello world"
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#
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# number variable (64 bit floating point)
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#
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h = 3.14
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print h
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#
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# string variable
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#
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str$ = "monkey"
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# strings can grow
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str$ &= " circus"
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print str$
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#
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# blocks end with 'end' or a dot, a newline has no
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# other meaning than a space
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#
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for i = 1 to 5
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sum += i * i
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.
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print sum
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#
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# functions have value and reference
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# parameters, no return values
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#
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func gcd a b . res .
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# a and b are value parameters
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# res is a reference parameter
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while b <> 0
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# h is a local variable, because
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# it is first used in the function
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h = b
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b = a mod b
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a = h
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.
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res = a
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.
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call gcd 120 35 r
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print r
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#
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# strings can be concatenated and numbers are
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# automatically converted to strings
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#
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print "1 + 2 = " & 1 + 2
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#
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# array of numbers
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#
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a[] = [ 2.1 3.14 3 ]
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#
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# arrays can grow
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a[] &= 4
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print a[]
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#
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# arrays, strings and numbers are copied by value
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#
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b[] = a[]
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a[] &= 4
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print a[] ; print b[]
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#
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# array swapping ist fast
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#
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swap a[] b[]
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print a[] ; print b[]
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#
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# array of strings
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#
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fruits$[] = [ "apple" "banana" "orange" ]
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#
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# for-in iterates over the elements of an array
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#
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for fruit$ in fruits$[]
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print fruit$
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.
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#
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# strings are also used for single characters
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#
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letters$[] = str_chars "ping"
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print letters$[]
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letters$[1] = "o"
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print str_join letters$[]
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#
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# 2-dimensional arrays are arrays of arrays
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# this defines 3 arrays with length 4
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#
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len a[][] 3
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for i range len a[][]
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len a[i][] 4
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.
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a[1][2] = 99
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print a[][]
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#
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# builtin functions
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if sin 90 = 1
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print "angles are in degree"
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.
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print pow 2 8
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# seconds since 1970
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print floor sys_time
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# random numbers
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print randomf
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print random 6 + 1
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#
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# hour and minutes
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print substr time_str sys_time 11 5
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#
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print str_ord "A"
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print str_chr 65
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#
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# set number format
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numfmt 0 4
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print sqrt 2
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print pi
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print logn 10
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#
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a$[] = str_split "10,15,22" ","
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print a$[]
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print 2 * number a$[0]
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print len a$[]
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print len "Hello"
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#
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# With 'break n' you can leave nested loops and a function
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#
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names$[] = [ ]
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func name2id name$ . id .
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for id range len names$[]
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if names$[id] = name$
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# leave loop and function
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break 2
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.
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.
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names$[] &= name$
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.
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call name2id "alice" id ; print id
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call name2id "bob" id ; print id
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call name2id "alice" id ; print i
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#
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# with 'repeat' you can make loops, which you can leave
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# in the loop body using 'until'
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#
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sum = 0
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repeat
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s$ = input
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until s$ = ""
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sum += number s$
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.
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print "sum: " & sum
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#
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# "input" reads a string from the "input_data" section,
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# if it exists, otherwise via a prompt.
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#
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input_data
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10
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-2
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6
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```
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Built-in graphic primitives and event-driven programming
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```
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# simple drawing with the mouse
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#
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set_linewidth 4
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set_color 900
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# the colors are coded from 0 to 999, with
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# the left digit specifying the red component,
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# the middle digit the green component and
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# the right digit the blue component.
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#
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on mouse_down
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down = 1
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move_pen mouse_x mouse_y
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# moves the drawing pen to the actual mouse position
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draw_circle 2
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.
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on mouse_up
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down = 0
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.
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on mouse_move
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if down = 1
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draw_line mouse_x mouse_y
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.
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.
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```
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```
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# an animated pendulum
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#
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on animate
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# The animate event occurs after each screen refresh.
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#
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clear_screen
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move_pen 50 50
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draw_circle 1
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x = 50 + 40 * sin ang
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y = 50 - 40 * cos ang
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draw_line x y
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draw_circle 5
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vel += sin ang / 5
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ang += vel
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.
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ang = 10
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```
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* [More about Easylang](https://easylang.online/)
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* [Source code](https://github.com/chkas/easylang)
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