Which library functions are missing from Rascal?

answered Jan 13

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updated Jan 13

Hossein
81 ● 8 ● 20

Here is another function I would add to list library this time: (another overload of the slice function)

list[&T] slice(list[&T] lst, int begin)

where the result is lst from begin onwards.

answered Dec 15 '11

Hossein
81 ● 8 ● 20

updated Dec 20 '11

Here are few minor features:

1. For str objects, we need something like pop_back(n) which will remove the n trailing characters of the string. n should obviously default to one.

2. For map, we need a function like remove_key(k) which removes the key k (and its respective value), if any. The current syntax, as far as I could dig it, is just so clumsy: m - (k: v), with arbitrary value v of the range type of m. If no such value exists, one needs to coin a random one! Not in every context this makes sense.

3. We need good wildcard support! We currently lack support for many reasonable usecases. Here is a very simple and pervasive example: m - (k: _).

answered Nov 08 '11

Radu Mereuta
96 ● 6

Working with SDF and Rascal, I found that I is much easier to design the grammar in SDF, because you can see the AST in a simple and compact form. Even if it is text, I could easily see that I forgot to put some follow restrictions or that some rules are ambiguous. I know that there are some functions that can allow you to see the parse tree in a compact way, but I couldn't make it to work, and I've seen that others had problems with it when they had ambiguities.

Also, can you have generic term composition and decomposition in the ParseTree and ADT?

answered Dec 20 '11

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updated Dec 20 '11

Dennisb
1 ● 2 ● 2

• A sum function for map, set, list etc;
• Simplify casting from value;
• A rounding function;
• Improvement of escape function, now you have to map all types of encoding;

These functions were important for outputting Series 1&2.

answered Dec 16 '11

Hossein
81 ● 8 ● 20

Here is another very minor one: writelnFile which is the file counterpart of println.

answered Jan 24

JasperT
33 ● 1 ● 5 ● 11

updated Jan 24

simple one: a join function on a list[str] and set[str] with a string of choice as glue. Thanks to Arjen:

import Set;
public str joinstr(list[str] L, str glue) = ("" | size(it) > 0 ? "<it><glue><e>" : "<e>" | str e <- L);
public str joinstr(set[str] S, str glue) = joinstr(toList(S), glue);

answered Jan 16

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updated Jan 24

Hossein
81 ● 8 ● 20

I cannot possibly help cursing Rascal for forcing me to write:

r.js = (r.js - (j: <j_name, false>)) + (j: <j_name, true>);

instead of

r.js[j][1] = true;

Full stop!!!

I wish I had also documented the error message that I got for it now works. But, it was something like "Internal Exception: ... not implemented yet" which made me sure that that's a problem with Rascal's current implementation.