MetaFun - Pragma ADE

30
i_111_222 := 1cm ;
i_[111]_[222] := 1cm ;
i_[111][222] := 1cm ;
draw
image (
draw (0cm,i_111_222) ;
draw (1cm,i_[111]_[222]) ;
draw (2cm,i_[111][222]) ;
)
withpen pencircle scaled 5mm
withcolor .625 red ;
Sometimes METAPOST ways are mysterious:
1.7 Conditions
The existence of boolean variables indicates the presence of conditionals. Indeed, the general form
of METAPOST's conditional follows:
if n=10 : draw p ; else : draw q ; fi ;
Watch the colons after the if and else clause. They may not be omitted. The semi--colons on the
other hand, are optional and depend on the context. You may say things like:
draw if n=10 : p ; else : q ; fi ;
Here we can omit a few semi--colons:
draw if n=10 : p else : q fi withcolor red ;
Adding semi--colons after p and q will definitely result in an error message, since the semi--colon
ends the draw operation and withcolor red becomes an isolated piece of nonsense.
There is no case statement available, but for most purposes, the following extension is adequate:
draw p withcolor if n