Print an equilateral triangle in J language

Question

I a trying to print a equilateral triangle to the console screen. this is what I could find

]\ 'hello' NB. which prints
h
he
hel
hell
hello

Answer 1

First solution that I came up with is this:

   eq=. ('b< >' 8!:2 (] ,.~ |.@}."1)@:([: >:/~ i.)) 
   eq 5
    1    
   111   
  11111  
 1111111 
111111111
   eq 10
         1         
        111        
       11111       
      1111111      
     111111111     
    11111111111    
   1111111111111   
  111111111111111  
 11111111111111111 
1111111111111111111

eq is a verb that first takes the argument and creates a matrix with the lower left of 1's using ([: >:/~ i.), this is then fed to (] ,.~ |.@}."1) which drops the first character of each line then reverses before appending to the original matrix. Finally, to get rid of the ugly 0's I use the foreign conjunction 8!:2 which formats the binary array into characters and the left argument 'b< >' specifies that 0's will be replaced with blank spaces.

Second solution:

   eq2=: ([ ,.~ |.@}."1)@:(]\) 
   eq2 'hello'
    h    
   ehe   
  lehel  
 llehell 
ollehello
   eq2 '*******'
      *      
     ***     
    *****    
   *******   
  *********  
 *********** 
*************

eq2 works the same way except it uses your ]\ initially which means that the format foreign conjunction is not necessary, as the result fed to ([ ,.~ |.@}."1) is already in character form.