Pascal

Niklaus Wirth designed Pascal at ETH Zurich in 1970 to teach structured programming: blocks with begin and end, procedures and functions, and a type for every variable, declared before use. Through the 1980s it was a common first language in schools and universities, and Turbo Pascal and later Delphi took it into commercial programs. Free Pascal is an open-source compiler for the modern dialect, compiled here with every warning treated as an error.

Its run-time library is larger than the language’s reputation suggests: SysUtils has string helpers such as Split, Math has Mean and Variance, and Generics.Collections has growable lists and sorting. The Free Component Library and Lazarus packages aren’t installed here.

Quirks

• The dialect depends on a mode switch. Without {$mode objfpc}, Integer is 16 bits and tops out at 32767; with it, Integer is 32 bits. Every program here starts with that switch.
• Without {$H+}, a String holds at most 255 characters and silently cuts off the rest.
• / always gives a real number, so 7 / 2 is 3.5. div is integer division, and -7 div 2 is −3: it rounds toward zero.
• Strings count from 1, but dynamic arrays count from 0, and a fixed array counts from whatever its type says, such as array[1..4].
• Range checks are off by default. With V: array[1..4] of Double, V[0] := 5 won’t compile, but I := 0; V[I] := 5 runs with no error and writes outside the array.
• WriteLn(x) prints a real as 2.9677500000000002E+001. x:0:6 asks for width 0 and six decimals.
• TDictionary from Generics.Collections triggers warnings in the library’s own code, so with warnings as errors, a program that uses it won’t compile. TList and TArrayHelper compile cleanly.
• Names aren’t case-sensitive: LENGTH(S) and Length(s) are the same call.

git clone https://github.com/qnixon/dswithx.git
cd dswithx
python3 harness/run_tests.py --language pascal