Languages in which whitespace is significant

Here's an incomplete list of the offendors:

Fortran

Horizontal whitespace is completely removed from your program! So you can say "GO TO" for "GOTO", but also

       DO 100 X=1.10

might not do what you think it does (note that's a period, not a comma!).

Haskell

Horizontal whitespace is used to specify block structure. However, a sane alternative (of using braces {...} to delimit blocks) is provided, but looks a bit funny.

Python

Horizontal whitespace must be used to specify block structure. Yuck.

Make

A very special type of horizontal whitespace must be used for command lines in the makefile: the first character of the line must be a TAB. Even 8 spaces won't work, but they'll look the same on your screen. Failing to do this leads to "amusing" errors.

The well-known assignment mentioned above (DO10I=1.10) is as awful as something like IF(1.EQ.J) - as you have to look ahead in your input stream. Continuation cards make things even worse - so do lesser-known facts ( every character but space and 0 are continuation characters). Besides, being able to write CO N T IN UE instead of CONTINUE is not something you'd ever need - nor is it helpful to spread "STOP" on four lines using continuation characters.

With Fortran 77, first compilers appeared which were less strict when it came to formatting (based on punched cards) and even allowed multiple statements on one line separated by a semicolon. (Besides, the use of INTEGER or LOGICAL arrays for character handling fell out of fashion with the introduction of CHARACTER).