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0 pointsadrian_b1y ago0 comments

But Pascal's variant records (1970-11) had very ugly design errors in comparison with the unions of Algol 68 (1968-12), which made them either useless or annoying for most applicatons.

Niklaus Wirth is well known as a critic of Algol 68 (before the design of Algol 68 was finalized), but in the case of his variant records he has completely failed to create something competitive.

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mzs1y ago

Doesn't look too bad particually the match tagged version last:

  MyType= (Scalar4, Real4, NullTerminatedStringC);
  
  MyUntaggedRecType=
      RECORD
      CASE MyType OF
      Scalar4: (longC:  ARRAY[1..150] OF longint);
      Real4:   (floatC: ARRAY[1..150] OF real);
      END;
  
  MyTaggedRecType=
      RECORD
      CASE tag: MyType OF
      Scalar4: (longC:  ARRAY[1..150] OF longint);
      Real4:   (floatC: ARRAY[1..150] OF real);
      END;
  
  ...
  
  { set all to 0.0 without running through the MC68881 }
  FOR j := 1 TO 150 DO
      longC[j]:= 0;
  
  ...
  
  CASE tag OF
      Scalar4: percentReal = longC[1];
      floatC:  percentReal = floatC[1]*100;
  ELSE
      percentReal = 0.0/0.0;

edit: don't have a pascal compiler handy, but that's the idea

pjmlp1y ago

Given where Algol 68 ended up, I would say Wirth was quite right.

adrian_bOP1y ago

Algol 68 was a failure mainly due to its inappropriate documentation, not due to the quality of the language.

It included many innovations that appeared again in other programming languages only decades later.

Niklaus Wirth was a good teacher and writer and the success of his languages is due mostly to his books and due to his languages being used for teaching in many universities, not due to their technical qualities.

pjmlp1y ago

I beg to differ, after Modula-2 and Object Pascal (Apple designed it with Wirth's feedback).

Most of his languages ended up losing, because they weren't being shipped with a free beer OS, coupled with a free beer compiler.

cryptonector1y ago

Algol 68 may have been a failure because it was ahead of its time, which meant it was hard to write a compiler for it. For example, Algol 68 had closures (apparently Knuth snuck them in).

peoplefromibiza1y ago

> not due to their technical qualities

AFAIK Pascal is C and Algol 68 is C++

people used Pascal because the compiler was blazing fast, it was easier to implement and learn and the features it lacked against Algol did not really matter most of the time (at the time)

More features doesn't automatically means "better"

Also Pascal had quite strong technical qualities, not very common among other contemporary languages

edit: can I ask the reason for the downvote? I would really like to hear an opinion on what Pascal did wrong, having used it extensively in the late 80s until the end of the 90s and why my comment was awarded with a negative score.

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mzs1y ago

Doesn't look too bad particually the match tagged version last:

  MyType= (Scalar4, Real4, NullTerminatedStringC);
  
  MyUntaggedRecType=
      RECORD
      CASE MyType OF
      Scalar4: (longC:  ARRAY[1..150] OF longint);
      Real4:   (floatC: ARRAY[1..150] OF real);
      END;
  
  MyTaggedRecType=
      RECORD
      CASE tag: MyType OF
      Scalar4: (longC:  ARRAY[1..150] OF longint);
      Real4:   (floatC: ARRAY[1..150] OF real);
      END;
  
  ...
  
  { set all to 0.0 without running through the MC68881 }
  FOR j := 1 TO 150 DO
      longC[j]:= 0;
  
  ...
  
  CASE tag OF
      Scalar4: percentReal = longC[1];
      floatC:  percentReal = floatC[1]*100;
  ELSE
      percentReal = 0.0/0.0;

edit: don't have a pascal compiler handy, but that's the idea

pjmlp1y ago

Given where Algol 68 ended up, I would say Wirth was quite right.

adrian_bOP1y ago

Algol 68 was a failure mainly due to its inappropriate documentation, not due to the quality of the language.

It included many innovations that appeared again in other programming languages only decades later.

pjmlp1y ago

I beg to differ, after Modula-2 and Object Pascal (Apple designed it with Wirth's feedback).

Most of his languages ended up losing, because they weren't being shipped with a free beer OS, coupled with a free beer compiler.

cryptonector1y ago

Algol 68 may have been a failure because it was ahead of its time, which meant it was hard to write a compiler for it. For example, Algol 68 had closures (apparently Knuth snuck them in).

peoplefromibiza1y ago

> not due to their technical qualities

AFAIK Pascal is C and Algol 68 is C++

people used Pascal because the compiler was blazing fast, it was easier to implement and learn and the features it lacked against Algol did not really matter most of the time (at the time)

More features doesn't automatically means "better"

Also Pascal had quite strong technical qualities, not very common among other contemporary languages

1 more reply

j / k navigate · click thread line to collapse