Hiding Types and Features

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With a feature structure system such as ALE, grammars and programs often manipulate very large feature structures. To aid in debugging, two queries allow the user to focus attention on particular types and features by supressing the printing of other types and features.

The following command supresses printing of a type:

| ?- no_write_type($T$).

After no_write_type($T$) is called, the type $T$ will no longer be displayed during printing. To restore the type $T$ to printed status, use:

| ?- write_type($T$).

If $T$ is a variable in a call to write_type/1, then all types are subsequently printed. Alternatively, the following query restores printing of all types:

| ?- write_types.

Features and their associated values can be supressed in much the same way as types. In particular, the following command blocks the feature $F$ and its values from being printed:

| ?- no_write_feat($F$).

To restore printing of feature $F$, use:

| ?- write_feat($F$).

If $F$ is a variable here, all features will subsequently be printed. The following special query also restores printing of all features.

| ?- write_feats.